This work was supported by funds from NIH (RO1-GMO97327) and the University Research Foundation (UPenn). We especially thank Svetlana Savina for her help in developing the immunohistochemistry protocol, Gordon Ruthel (University of Pennsylvania) and the Penn Vet Imaging Core for assistance with microscopy and Leslie King, Ph.D. for critical reading this manuscript.

All methods described here were carried out in strict accordance with the recommendations in the National Institutes of Health Guide for the Care and Use of Laboratory Animals provided by the Institute of Laboratory Animal Resources and were approved by the Institutional Animal Care and Use Committee of the University of Pennsylvania.
All tools and equipment for the methods are shown in Figure 1 and listed in the Table of Materials.
1 . Mouse eye enucleation, eye cup dissection, and embedding
<ol>
	<li>Euthanize mice with carbon dioxide (CO2) followed by either decapitation (postnatal mice P0 - P11) or cervical dislocation (adult &#62;P11 mice). For P0-P14 mice, eyes are covered by skin. Ensure to remove the skin prior to subsequent steps.</li>
	<li>Mark the temporal part of the eye (Figure 2A) by slightly burning the cornea using a tail cauterizer. Avoid burning a hole in the cornea by touching the cornea very lightly and for no more than a split second with the cauterizer.</li>
	<li>Immediately enucleate mouse eyes using curved Dumont #5/45 forceps. Incubate for 15 min in a 1.5 mL cryotube tube with 1 mL of 4% paraformaldehyde (PFA) in phosphate-buffered saline (PBS) on ice.</li>
	<li>After 15 min in 4% PFA, transfer the fixed eye using the curved forceps Dumont #5/45 to a modified 35 mm dissection dish (see Table of Materials and Figure 1C) filled with PBS and place under dissecting microscope.</li>
	<li>Make a small incision at the burn mark, perpendicular to and just above the limbus (border of the cornea) using the micro knife.</li>
	<li>Insert the curved scissors into the incision and perform a circumferential cut of the cornea following the limbus (Figure 2B).</li>
	<li>Remove the cornea and extract the lens with a thin Dumont #5 forceps, (Figure 2B) and lift it delicately away from the posterior portion of the eye. The vitreous body, the clear gel that fills the space between the lens and the retina, will come out with the lens (Figure 2B) and the retina will be visible as a white surface covering the inside of the posterior eye cup. Ensure that there is no visible damage to the retina, such as holes or tears (Figure 2C).</li>
	<li>Wash the eye cups twice in 1 mL of PBS for 10 min at room temperature.</li>
	<li>Cryoprotect the eye cups by equilibrating them in a solution of 15% sucrose in PBS overnight at 4 &#176;C until the eye cup sinks</li>
	<li>Transfer the eye cups to 30% sucrose in PBS for 2-3 h until the eye cup sinks.</li>
	<li>Embed the eye cups in OCT in 10 x 10 mm cryomolds (Figure 3A). Using a dissecting microscope, orient the eye in the cryomold along its dorsal-ventral axis (Figure 2D, Figure 3A) by rotating the eye until the burn mark is on top, the optic nerve is on the left and the cut-out part of the mold faces the right (Figure 2D). Take care to avoid bubbles near the tissue. 
	NOTE: To manipulate the eye cup, use a titanium probe made of a titanium wire attached to a pipette tip.</li>
	<li>To snap-freeze retinal tissue, immerse the cryomold for at least 5 min in a metal beaker containing isopentane and place the beaker in liquid nitrogen or dry ice/100% ethanol bath (up to 1/3 of the height of the metal beaker). 
	NOTE: The cryomold should be immersed in isopentane to greater than half of its height but does not have to be completely submerged.</li>
	<li>Remove the frozen block and wrap it in aluminum foil.</li>
	<li>Store at -80 &#176;C.</li>
	<li>Mark the frozen block using a pen or sharpie to record the orientation of the block (Figure 3B).</li>
</ol>
2 . Sectioning using a cryostat
<ol>
	<li>After adjusting the cryostat temperature (between -20 and -25 &#176;C), allow the molds containing the embedded eye cups to equilibrate to the cryostat temperature for 1 h.</li>
	<li>Install the block with dorso-ventral orientation (Figure 3C) and cut 10 &#181;m thick serial sections. Carefully place the retinal sections on annotated and numbered microscope slides.</li>
	<li>Store slides in slide boxes at -20 &#176;C or -80 &#176;C until IHC procedures.</li>
</ol>
3 . Fluorescence immunostaining using the Slide Rack
NOTE: The Slide Rack system (e.g., Sequenza) holds the glass microscope slides with a cover plate, creating a ~100 &#181;L capillary gap between the slide and the plate.
<ol>
	<li>Thaw the cryo-sections at room temperature (RT) for 2 h to 4 h to allow them to dry and attach to microscope slides. 
	NOTE: It is also possible to dry them at 30-37 &#176;C for 30 min to 1 h.</li>
	<li>Place slides in Slide Rack and wash the retinal sections twice in 100-200 &#181;L PBS for 2 min.</li>
	<li>Permeabilize the retinal sections by incubating them in 0.25% Triton-X / 0.05% NaN3in PBS for 5 min at RT.</li>
	<li>Add 100 &#181;L of blocking solution to the slides.</li>
	<li>Add 100 &#181;L of primary antibody diluted in blocking solution to the slides.</li>
	<li>Incubate retinal sections overnight at 4 &#730;C. 
	NOTE: During this time, cover the Slide Rack to avoid desiccation of the sections.</li>
	<li>Wash the retinal sections 3 times, each for 15 min, using 200 &#181;L PBS. 
	NOTE: The addition of 0.001- 0.002% Triton-X100 to PBS (PBS-T) allow a more stringent wash but can disrupt some membranes and cellular structures.</li>
	<li>Incubate retinal sections in fluorescent-labeled secondary antibodies for 1 h at RT. From now on protect from light.</li>
	<li>Wash the retinal sections 3 times, each for 15 min.</li>
	<li>Incubate the retinal sections at RT for 5 min with a nuclear marker such as Hoechst 33342 or DAPI solution.</li>
	<li>Wash the retinal sections 1 time for 15 min.</li>
	<li>Place a coverslip on top of a paper towel on the lab bench.</li>
	<li>Add 2 drops of anti-fading mounting media to the center of the coverslip.</li>
	<li>Turn the slide over to have the retinal cryo-section facing down.</li>
	<li>Carefully mount the coverslip slowly, at a ~45&#730; angle, tip the slide onto the mounting media. 
	NOTE: Avoiding forming bubbles as you lower the slide in place.</li>
	<li>Apply even pressure, using a heavy book or catalog (see below), to the slide-coverslip combination to eliminate excess mounting media. 
	NOTE: To ensure consistency in sample preparation, always use the same object, (i.e., the same book or catalog) to apply even pressure to the coverslip during slide mounting.</li>
	<li>Keep flat and allow to harden overnight at RT in the dark. Store slides flat at 4 &#176;C indefinitely.</li>
	<li>Image via wide field or confocal fluorescence microscopy (Figure 4).</li>
</ol>

<ol>
	<li>Coons, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Labelled+antigens+and+antibodies.">Labelled antigens and antibodies.</a> Annual Review of Microbiology. 8, 333-352 (1954).</li><li>Coons, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescent+antibodies+as+histochemical+tools.">Fluorescent antibodies as histochemical tools.</a> Federation Proceedings. 10 (2), 558-559 (1951).</li><li>Coons, A. H., Kaplan, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Localization+of+antigen+in+tissue+cells;+improvements+in+a+method+for+the+detection+of+antigen+by+means+of+fluorescent+antibody.">Localization of antigen in tissue cells; improvements in a method for the detection of antigen by means of fluorescent antibody.</a> Journal of Experimental Medicine. 91 (1), 1-13 (1950).</li><li>Chatterjee, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Artefacts+in+histopathology.">Artefacts in histopathology.</a> Journal of Oral Maxillofacial Pathology. 18 (Suppl 1), S111-S116 (2014).</li><li>Hartz, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Frozen+sections+from+Bouin-fixed+material+in+histopathology.">Frozen sections from Bouin-fixed material in histopathology.</a> Stain Technology. 20, 113 (1945).</li><li>Benerini Gatta, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+alternative+fixatives+to+formalin+in+diagnostic+pathology.">Application of alternative fixatives to formalin in diagnostic pathology.</a> European Journal of Histochemistry. 56 (2), e12 (2012).</li><li>Tokuyasu, K. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+cryoultramicrotomy+to+immunocytochemistry.">Application of cryoultramicrotomy to immunocytochemistry.</a> Journal of Microscopy. 143 (Pt 2), 139-149 (1986).</li><li>Imai, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+properties+of+rhodopsin+and+rod+function.">Molecular properties of rhodopsin and rod function.</a> Journal of Biological Chemistry. 282 (9), 6677-6684 (2007).</li><li>Lee, J. W., Lim, M. Y., Park, Y. S., Park, S. J., Kim, I. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reexamination+of+Dopaminergic+Amacrine+Cells+in+the+Rabbit+Retina:+Confocal+Analysis+with+Double-+and+Triple-labeling+Immunohistochemistry.">Reexamination of Dopaminergic Amacrine Cells in the Rabbit Retina: Confocal Analysis with Double- and Triple-labeling Immunohistochemistry.</a> Experimental Neurobiology. 26 (6), 329-338 (2017).</li><li>Bringmann, A., Grosche, A., Pannicke, T., Reichenbach, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GABA+and+Glutamate+Uptake+and+Metabolism+in+Retinal+Glial+(Muller)+Cells.">GABA and Glutamate Uptake and Metabolism in Retinal Glial (Muller) Cells.</a> Frontiers in Endocrinology (Lausanne). 4, 48 (2013).</li><li>Nakhai, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ptf1a+is+essential+for+the+differentiation+of+GABAergic+and+glycinergic+amacrine+cells+and+horizontal+cells+in+the+mouse+retina.">Ptf1a is essential for the differentiation of GABAergic and glycinergic amacrine cells and horizontal cells in the mouse retina.</a> Development. 134 (6), 1151-1160 (2007).</li><li>Applebury, M. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+murine+cone+photoreceptor:+a+single+cone+type+expresses+both+S+and+M+opsins+with+retinal+spatial+patterning.">The murine cone photoreceptor: a single cone type expresses both S and M opsins with retinal spatial patterning.</a> Neuron. 27 (3), 513-523 (2000).</li></ol>

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Mouse retina dissection is a delicate process due to the small size and shape of mouse eyes and the fragility of retinal tissue. Even though performing high-quality dissection is a matter of practice, having a detailed protocol, providing efficient methods and tips is a necessity to obtain retinal sections and IHC. In addition to the protocols described here, there are several tips that allow for consistent high-quality retinal sections that are suitable for reproducible IHC.
Prior to commencing with dissection, it is important to be comfortable, relaxed and set the room lighting for optimal vision during mouse eye microdissection. To maintain mouse eye cup shape while dissecting the eye, we suggest keeping eyes submerged in PBS in custom made wax-coated dissection dishes. We suggest coating a 35mm dissection dish with light pink colored dental wax (Figure 1C). Indeed, the light pink color of the dental wax provides adequate contrast to see readily eye structures under a dissection scope, the eye-sized impressions in the wax, made by pressing the base of microfuge tubes into the wax, will keep the eye cup in place while allowing the appropriate rotation of the tools around the eye cup during the dissection. In addition, it is important to remove as much vitreous fluid from the eye cup as possible while removing the lens, as residual vitreous fluid is prone to form tissue damaging ice crystals during the tissue block freezing step. We generally use a tissue paper and place it to the border of the dissected eye cup, to carefully remove all remaining vitreous fluid by capillary without disturbing the retina tissue. In the unfortunate case where a small amount of residual vitreous fluid is still present in the eye cup, sectioning should be done at -20 &#176;C to reduce transformation of the vitreous in ice and therefore preserve the sharpness of the blade and the quality of the sectioning.
Fixation and embedding methods also have a major impact on the quality of the sections and the IHC. Although formalin-fixed paraffin-embedded sections yield optimal structural integrity of the eye tissue, formalin contains methanol that can enhance background fluorescence. To avoid these artifacts, we recommend using fresh EM grade paraformaldehyde (PFA) to limit background and autofluorescence caused by methanol or oxidized PFA4,5,6. We recommend the mild fixation conditions described in our protocol fixing the eye with 4% paraformaldehyde for 15 min on ice. Since PFA rapidly penetrates the tissue, but cross-links proteins very slowly, those conditions are sufficient to preserve retinal structural integrity during the dissection and preserve the antigenicity of common retinal antigens without the need for antigen retrieval methods4. If the retina structure is not well preserved, the duration of PFA fixation can be increased, however it is important to be aware that over-fixating tissues will enhance non-specific background fluorescence and can lead to epitope masking, while under-fixating tissues may compromise structural integrity of the tissue and cause the loss of some antigens prone to proteolytic degradation. Since short time PFA incubation is a relatively mild fixation, we also recommend snap-freezing retinas by dipping the OCT-embedded eye, contained in a cryomold (10 mm x 10 mm x 5 mm), in an isopentane bath immersed in liquid nitrogen. Snap-freezing tissues will preserve antigens, while sucrose solution and OCT act as cryo-protectants. This method will reduce the distortion of the tissue due to the formation of ice crystals, which can cause the so-called Swiss Cheese type of tissue damage. The cryomold should not be dipped directly in liquid nitrogen or it will start to boil, forming a vapor barrier and that will slow the freezing process, resulting in a heterogeneous fixation and preservation. Moreover, tissue and OCT in contact with liquid nitrogen can crack, thereby affecting the integrity of the eye7. We, therefore, recommend dipping the cryomold (10 mm x 10 mm x 5 mm) in no more than 5 mm deep isopentane using a small stainless-steel beaker, itself dipped in a larger stainless-steel beaker (100 mm wide minimum) containing liquid nitrogen. To avoid the rapid evaporation of the liquid nitrogen during the preparation of several samples, we keep both baths in an insulated cooler. It should be noted that cryopreserving tissues in OCT is not a long-term preservation method, due to the formation of ice crystals in the tissue over time which can alter subcellular morphology and/or denature some antigens. Consequently, tissue blocks and frozen sections should be stored at -20 &#176;C for short-term storage and for -80 &#176;C long-term storage.
The mammalian retina is an asymmetric organ with a specific spatial distribution of the cells across the temporal-nasal and dorso-ventral axes. For example, M- and S-opsin cones are arranged in a specific dorso-ventral gradient 12. Therefore, it is essential to ensure proper orientation of the eye throughout tissue preparation and sectioning in order to perform comparative IHC. We use a cauterizer to place a reference mark on the eye prior to dissection (Figure 2A, D) so that we can orient the eye cup along its dorsal-ventral axis during the embedding phase, and therefore obtaining perfectly transverse sections. We place the burn mark on the dorso-temporal part of the eye, by touching the cornea for a split second with the cauterizer. This will allow to slightly burn the cornea while avoiding piercing a hole into it. During the eye cup dissection, we make a small incision, at the burn mark, perpendicular to border of the cornea, using the micro knife (Figure 2B). To facilitate the dorso-ventral orientation of the block and minimize orientation adjustments during sectioning, we suggest orienting the posterior eye cup in the cryomold, with the burn mark facing the bottom of the cryomold and the opening of the cornea perfectly parallel of the cryomold&#39;s right side (Figure 3A, B). The frozen block will be installed with the bottom of the block facing toward the blade in the cryostat, the eye cup perpendicular to the blade, in a dorso-ventral orientation (Figure 3c).
Reliable retina IHC starts with optimal, adapted, and reproducible dissections and tissue processing. The method outlined here optimally preserves retinal structure and integrity while minimizing autofluorescence and epitope masking that can compromise fluorescent IHC. Following this protocol will ensure that you have reproducible high-quality data.

Immunohistochemistry (IHC) is a powerful technique for localizing specific proteins and cellular structures in tissues in situ1,2,3. Inappropriate fixation methods and sub-optimal sectioning of complex tissues can disrupt tissue structure, generate high background staining or diminish antibody-epitope interactions, resulting in staining artifacts and consequent misinterpretation of IHC data4. As the vertebrate retina is a complex and highly organized neural organ composed of strata of interconnected photoreceptors, interneurons and ganglion cells, it is very fragile and can be easily disrupted during dissection and sectioning. A detailed, standardized, and validated protocol from mouse eye dissection and orientation to immunostaining will help significantly reduce IHC artifacts, thereby, increasing the reliability of the results and allowing for more accurate comparative data analysis.
There are many protocols for tissue preparation for IHC, however, not all are suitable for retinal tissue. Strong fixatives like 10% formalin or Bouin&#39;s solution preserve retinal structure during dissection and sectioning5. Unfortunately, strong fixatives often lead to the enhanced background fluorescence and epitope masking due to the chemical modification of epitopes6. On the other hand, milder fixatives, like 4% paraformaldehyde (PFA) can alleviate some of these artifacts but require meticulous dissection and sectioning to preserve the optimal retinal structure. PFA rapidly penetrates tissue, but cross-links proteins very slowly, reducing the risk of epitope masking. Since short time PFA incubation is a relatively mild fixation, tissues often require rapid freezing to preserve antigens. It is important to avoid ice crystal formation during tissue freezing as they distort and damage the integrity of cells and tissues7.
Here we describe detailed and standardized protocols for dissection, fixation, and cryo-protection of mouse ocular posterior cups that yield consistent and reliable IHC data.

<table border="0" cellpadding="0" cellspacing="0" style="width:1128px;" width="1129">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">6qt. Stainless Steel Beaker (185 x 218mm)</td>
			<td style="width:209px;">Gilson&#160;</td>
			<td style="width:236px;">#MA-48</td>
			<td style="width:365px;">For liquid nitrogen (Figure 1E)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Aluminum foil&#160;</td>
			<td style="width:209px;"></td>
			<td style="width:236px;"></td>
			<td style="width:365px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Cauterizer&#160;</td>
			<td style="width:209px;">Bovie</td>
			<td style="width:236px;">#AA01</td>
			<td style="width:365px;">To mark eye orientation (Figure 1A)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:317px;">Curved forceps, Dumont #5/45 tweezers, 45-degrees bent&#160;</td>
			<td style="width:209px;">Electron Microscopy Sciences</td>
			<td style="width:236px;">#72703-D</td>
			<td style="width:365px;">For mouse eye enucleation and maintenance (Figure 1A)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:317px;">Curved scissors, Vannas Spring Scissors - 2.5mm Cutting Edge&#160;</td>
			<td style="width:209px;">Fine Science Tools&#160;</td>
			<td style="width:236px;">#15002-08</td>
			<td style="width:365px;">To circumferentially cut the cornea (Figure 1B)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Dental wax-coated 35mm dissection dish</td>
			<td style="width:209px;"></td>
			<td style="width:236px;"></td>
			<td style="width:365px;">For eye cup dissection (Figure 1C)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:317px;">Dissecting microscope&#160;</td>
			<td style="width:209px;">Leica, Houston, USA&#160;</td>
			<td style="width:236px;">MZ12.5 High-performance stereomicroscope</td>
			<td style="width:365px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:317px;">Micro Knives - Plastic Handle&#160;</td>
			<td style="width:209px;">Fine Science Tools&#160;</td>
			<td style="width:236px;">#10315-12</td>
			<td style="width:365px;">To make a small incision at the burn mark (Figure 1A)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Pink dental wax&#160;</td>
			<td style="width:209px;">Electron Microscopy Sciences&#160;</td>
			<td style="width:236px;">#72660</td>
			<td style="width:365px;">For coating dissection dish</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Slide Rack and Coverplate</td>
			<td style="width:209px;">Ted Pella</td>
			<td style="width:236px;">#36107</td>
			<td style="width:365px;">For retinal IHC (Figure 1G)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Stainless Steel Beaker (89 x 114mm)</td>
			<td style="width:209px;">Gilson&#160;</td>
			<td style="width:236px;">#MA-40</td>
			<td style="width:365px;">For isopentane bath (Figure 1E)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Styrofoam box</td>
			<td style="width:209px;"></td>
			<td style="width:236px;"></td>
			<td style="width:365px;">For insulated cooler</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:317px;">Thin forceps Dumont #5&#160;&#160;</td>
			<td style="width:209px;">Fine Science Tools&#160;</td>
			<td style="width:236px;">#11254-20</td>
			<td style="width:365px;">To remove the cornea and extract the lens (Figure 1B)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:317px;">Tissue-Tek cryomold&#160; (10mm x 10mm x 5mm)</td>
			<td style="width:209px;">Electron Miscroscopy Sciences&#160;</td>
			<td style="width:236px;">#62534-10</td>
			<td style="width:365px;">Mold for OCT embedding</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Buffers and Reagents</td>
			<td style="width:209px;">Company</td>
			<td style="width:236px;">Catalog Number</td>
			<td style="width:365px;">Comments</td>
		</tr>
		<tr height="58">
			<td height="58" style="height:58px;width:317px;">Blocking solution</td>
			<td style="width:209px;"></td>
			<td style="width:236px;"></td>
			<td style="width:365px;">2% Normal Horse Serum, 1.5% Cold Fish skin Gelatin (at 40-50% in H2O, cat #G7765), 5% bovine serum albumin (cat #AK1391-0100) in permeabilization buffer.&#160;&#160;</td>
		</tr>
		<tr height="77">
			<td height="77" style="height:77px;width:317px;">Gelvatol (anti-fading mounting media)</td>
			<td style="width:209px;"></td>
			<td style="width:236px;"></td>
			<td style="width:365px;">Under the fume hood, dissolve 0.337g DABCO (Sigma cat #D2522-25G) in 10mL Fluoromount G (Fisher cat #OB100-01).&#160; Adjust to pH 8-8.5 with 12N HCl (~ 5 drops).&#160; Store in amber drop bottle at 4&#176;C&#160; (8).&#160;</td>
		</tr>
		<tr height="58">
			<td height="58" style="height:58px;width:317px;">Hoechst 33342 1000x Stock</td>
			<td style="width:209px;">Thermo Scientific</td>
			<td style="width:236px;">#62249</td>
			<td style="width:365px;">1 mg/ml in PBS (1000x). Aliquot and store in dark, at 4&#176;C for up to 1 year or at -20&#176;C for long term storage. Prepare fresh&#160; at 1 ug/mL (1x)&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Isopentane, 99%&#160;</td>
			<td style="width:209px;">GFS Chemicals</td>
			<td style="width:236px;">#2961</td>
			<td style="width:365px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Liquid Nitrogen</td>
			<td style="width:209px;"></td>
			<td style="width:236px;"></td>
			<td style="width:365px;"></td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:317px;">Paraformaldehyde (PFA) in PBS</td>
			<td style="width:209px;">Electron Microscopy Sciences&#160;</td>
			<td style="width:236px;">#15710</td>
			<td style="width:365px;">Prepared fresh 4% PFA from 16% PFA stock. Store the remaining 16% PFA at 4&#176;C in the dark.&#160;</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:317px;">Permeabilization solution</td>
			<td style="width:209px;"></td>
			<td style="width:236px;"></td>
			<td style="width:365px;">PBS + 0.25% Triton-X (AMRESCO cat #0694-1L) + 0.05% NaN3.&#160; Prepare fresh.</td>
		</tr>
		<tr height="50">
			<td height="50" style="height:50px;width:317px;">Phosphate-buffered saline (PBS)</td>
			<td style="width:209px;">Bioworld&#160;</td>
			<td style="width:236px;">#41620015-20</td>
			<td style="width:365px;">0.02 g/L KCl, 0.02 g/L KH2PO4, 0.8 g/L NaCl, 0.216 g/L Na2HPO4 , pH 7.4.&#160; Prepared from 10x stock&#160;</td>
		</tr>
		<tr height="58">
			<td height="58" style="height:58px;width:317px;">Sucrose solutions</td>
			<td style="width:209px;">Fisher Scientific&#160;&#160;</td>
			<td style="width:236px;">#S-5-500</td>
			<td style="width:365px;">Dissolve the appropriate amount of sucrose in&#160; 37&#176;C PBS (takes ~15 min to dissolve). May be stored for a few days at 4&#176;C.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Tissue-Tek OCT-compound&#160;</td>
			<td style="width:209px;">Sakura</td>
			<td style="width:236px;">&#160;#4583</td>
			<td style="width:365px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:317px;">Antibodies</td>
			<td style="width:209px;">Company</td>
			<td style="width:236px;">Catalog Number</td>
			<td style="width:365px;">Comments</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:317px;">anti-calbindin</td>
			<td>Sigma-Aldrich</td>
			<td>C8666</td>
			<td>To label horinzotal cells&#160;</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:317px;">anti-GAD65</td>
			<td>Chemicon</td>
			<td>AB5082</td>
			<td>To label GABAergic amacrine cells</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:317px;">anti-GS</td>
			<td>BD Transduction</td>
			<td>610517</td>
			<td>To label M&#252;ller cells</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:317px;">anti-rhodopsin</td>
			<td>Millipore</td>
			<td>MAB5316</td>
			<td>To label rods</td>
		</tr>
	</tbody>
</table>

preparation of mouse retinal cryo-sections for immunohistochemistry

Preparation of high-quality mouse eye sections for immunohistochemistry (IHC) is critical for assessing the retinal structure and function and for determining the mechanisms underlying retinal diseases. Maintaining structural integrity throughout the tissue preparation is vital for obtaining reproducible retinal IHC data but can be challenging due to the fragility and complexity of retinal cytoarchitecture. Strong fixatives like 10% formalin or Bouin's solution optimally preserve the retinal structure, they often impede IHC analysis by enhancing the background fluorescence and/or diminishing antibody-epitope interactions, a process known as epitope masking. Milder fixatives, on the other hand, like 4% paraformaldehyde, reduces background fluorescence and epitope-masking, meticulous dissection techniques must be utilized to preserve the retinal structure. In this article, we present a comprehensive method to prepare mouse ocular posterior cups for IHC that is sufficient to preserve most antibody-epitope interactions without loss of retinal structural integrity. We include representative IHC with antibodies to various retinal cell type markers to illustrate tissue preservation and orientation under optimal and sub-optimal conditions. Our goal is to optimize IHC studies of the retina by providing a complete protocol from ocular posterior cup dissection to IHC.

To illustrate how these protocols, ensure optimal retinal preservation for IHC, we probed retinal sections from P28 WT mice (C57BL/6N) with antibodies to rhodopsin (a photoreceptor marker)8, glutamic acid decarboxylase 65 (Gad65, an amacrine cell marker)9, glutamine synthetase (GS, a M&#252;ller cell marker)10, and calbindin (a horizontal cell marker)11&#160;(Figure 4). IHC indicate that our protocols consistently yield high quality and well-preserved retinal sections. Notably, the rhodopsin-rich inner and outer segments remain vertical and intact with little to no separation from overlying the retinal pigmented epithelium (RPE) (Figure 4A). In addition, M&#252;ller cells remain well-preserved with soma properly aligned and cytoplasmic processes that span from the ganglion cell layer (GCL) to the outer nuclear layer (ONL) (Figure 4B).
Interneurons, such as Gad65-positive amacrine cells, also remain properly stratified within the INL and inner plexiform layer (IPL) (Figure 4B) while well-defined horizontal cells are detectable at the INL and outer plexiform layer (OPL) border (Figure 4C). Collectively, these data demonstrate that our method preserves retinal cell and tissue integrity, from photoreceptors to ganglion cells
To facilitate transverse sectioning, it is important to meticulously orientate the optical cup in the cryo-mold prior to freezing. Misoriented retinas, poor sectioning technique or sectioning with dull or damaged microtome knives can cause artifacts such as retinal tissue tears, distortions, and cellular displacement, as in Figure 4. Examples of section artifacts are shown in Figure 4D-F. In Figure&#160;4D poor sectioning and alignment lead to photoreceptor inner and outer segments distortion (Figure 4D) and small tissue tears (Figure 4E, arrow). In another example, poor tissue orientation prior to section leads to sub-optimal alignment of Muller cell soma and cytoplasmic processes Figure 4E. Figure 4F shows how poor sectioning likely caused by a dull microtome knife caused horizontal cells to aberrantly smear from the OPL to the GCL. Thus, precise attention must be applied to the execution of each step outlined in the protocol to ensure the highest quality and reproducibility of IHC data.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/59683/59683fig1.jpg" /> 
Figure 1: Tools for mouse eye dissection, embedding, and IHC. (A) Cauterizer; (B) Dissection tools from left to right: Dumont #5/45 curved forceps, Curved scissors, and Dumont #5 thin forceps; (C) 35 mm dissection dish (arrow points to dissecting chamber); (D) Dissecting microscope; (E) Frozen tools from left to right: Insulated cooler, stainless steel beaker for isopentane bath , stainless steel liquid N2 bath; (F) titanium probe; (G) Slide Rack and Coverplate for IHC. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59683/59683fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/59683/59683fig2.jpg" /> 
Figure 2: Mouse eye cup orientation and description. (A) Temporal burn mark location (red arrow) to facilitate eye orientation (dorso = D, ventral = V, temporal = T, nasal = N). (B) Schematic for mouse eye dissection. A small incision is made at the burn mark, perpendicular into the cornea and just above the limbus using a fine scalpel (Micro knife). Cut around the cornea to separate the anterior and posterior part of the eye. (C) Eye cup with an intact retina. (D) Dorso-ventral orientation of mouse eye with the optic nerve (ON), lens (L), cornea (C) the limbus (OS). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59683/59683fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/59683/59683fig3.jpg" /> 
Figure 3: Mouse eye embedding. (A) Dorso-ventral orientated mice eye cup in cryomold filled with OCT, (B) Frozen mouse retinal cup in annotated cryomold. (C) Cryostat. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59683/59683fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/59683/59683fig4.jpg" /> 
Figure 4: Mouse retina immunohistochemistry.(A-C) Good quality and (D-F) poor quality retinal sections from P28 WT were labeled with antibodies to the rhodopsin (A, C) amacrine marker GAD65 (B, E) and the Mu&#776;ller cell marker glutamine synthetase (GS; B, E), and horizontal cell marker calbindin (C, F). White arrows point to tissue tears and aberrant smearing of the tissue. Scale bar, 20 &#181;m. Nuclei labeled with Hoechst 33342 (blue). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59683/59683fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Preparation of Mouse Retinal Cryo-sections for Immunohistochemistry at JoVE.com

Preparation of Mouse Retinal Cryo-sections for Immunohistochemistry

This report describes comprehensive methods for preparing frozen mouse retina sections for immunohistochemistry (IHC). Methods described include dissection of the ocular posterior cup, paraformaldehyde fixation, embedding in Optimal Cutting Temperature (OCT) media and tissue orientation, sectioning and immunostaining.

Preparation of high-quality mouse eye sections for immunohistochemistry (IHC) is critical for assessing the retinal structure and function and for ...

preparation-of-mouse-retinal-cryo-sections-for-immunohistochemistry

Nanyang Technological University

Research

JoVE Journal

Neuroscience

27.1K Views.  University of Pennsylvania School of Veterinary Medicine. This report describes comprehensive methods for preparing frozen mouse retina sections for immunohistochemistry (IHC). Methods described include dissection of the ocular posterior cup, paraformaldehyde fixation, embedding in Optimal Cutting Temperature (OCT) media and tissue orientation, sectioning and immunostaining.

Video: Preparation of Mouse Retinal Cryo-sections for Immunohistochemistry

Preparation of Mouse Brain Tissue for Immunoelectron Microscopy

Transmission electron microscopy (TEM) is extremely useful for visualizing microglial, oligodendrocytic, astrocytic, and neuronal subcellular compartments (dendrite, dendritic spine, axon, axon terminal, perikaryon), as well as their intracellular organelles and cytoskeleton, in the central nervous system at high spatial resolution. Combined with TEM, pre-embedding immunocytochemistry allows the discrimination of cellular elements with few distinctive features and identification criteria (e.g., microglial perikarya and processes, when using an antibody against the microglia-specific marker Iba1 (ionized calcium binding adaptor molecule 1; as presented here)), identifying the neurotransmitter contents of cellular elements (e.g., serotonergic) and their ultrastructural localization of soluble or membrane-bound proteins (e.g., 5 HT1A and EphA4 receptors). Here, we describe a protocol for transcardiac perfusion of mice with acrolein fixative, removal and sectioning of the brain, as well as immunoperoxidase-diaminobenzidine (DAB) staining, resin embedding, and ultrathin sectioning of the brain sections. Upon completion of these procedures, the immunostained material is ready for examination with TEM. When rigorously performed, this technique provides an excellent compromise between optimal ultrastructural preservation and immunocytochemical detection.

We describe a protocol for transcardiac perfusion of mice, removal and sectioning of the brain, as well as immunoperoxidase staining, resin embedding, and ultrathin sectioning of the brain sections. Upon completion of these procedures, the immunostained material is ready for examination with transmission electron microscopy.

Transmission electron microscopy (TEM) is extremely useful for visualizing microglial, oligodendrocytic, astrocytic, and neuronal subcellular compartments ...

Patch Clamp Recordings from Mouse Retinal Neurons in a Dark-adapted Slice Preparation

Our visual experience is initiated when the visual pigment in our retinal photoreceptors absorbs photons of light energy and initiates a cascade of intracellular events that lead to closure of cyclic-nucleotide-gated channels in the cell membrane. The resulting change in membrane potential leads in turn to reductions in the amount of neurotransmitter release from both rod and cone synaptic terminals. To measure how the light-evoked change in photoreceptor membrane potential leads to downstream activity in the retina, scientists have made electrophysiological recordings from retinal slice preparations for decades1,2. In the past these slices have been cut manually with a razor blade on retinal tissue that is attached to filter paper; in recent years another method of slicing has been developed whereby retinal tissue is embedded in low gelling temperature agar and sliced in cool solution with a vibrating microtome3,4. This preparation produces retinal slices with less surface damage and very robust light-evoked responses. Here we document how this procedure can be done under infrared light to avoid bleaching the visual pigment.

Here we describe a procedure for generating dark-adapted slices of the mouse retina for electrophysiological recordings.

Our visual experience is initiated when the visual pigment in our retinal photoreceptors absorbs photons of light energy and initiates a cascade of ...

An Isolated Retinal Preparation to Record Light Response from Genetically Labeled Retinal Ganglion Cells

The first steps in vertebrate vision take place when light stimulates the rod and cone photoreceptors of the retina 1. This information is then segregated into what are known as the ON and OFF pathways. The photoreceptors signal light information to the bipolar cells (BCs), which depolarize in response to increases (On BCs) or decreases (Off BCs) in light intensity. This segregation of light information is maintained at the level of the retinal ganglion cells (RGCs), which have dendrites stratifying in either the Off sublamina of the inner plexiform layer (IPL), where they receive direct excitatory input from Off BCs, or stratifying in the On sublamina of the IPL, where they receive direct excitatory input from On BCs. This segregation of information regarding increases or decreases in illumination (the On and Off pathways) is conserved and signaled to the brain in parallel.
The RGCs are the output cells of the retina, and are thus an important cell to study in order to understand how light information is signaled to visual nuclei in the brain. Advances in mouse genetics over recent decades have resulted in a variety of fluorescent reporter mouse lines where specific RGC populations are labeled with a fluorescent protein to allow for identification of RGC subtypes 2 3 4 and specific targeting for electrophysiological recording. Here, we present a method for recording light responses from fluorescently labeled ganglion cells in an intact, isolated retinal preparation. This isolated retinal preparation allows for recordings from RGCs where the dendritic arbor is intact and the inputs across the entire RGC dendritic arbor are preserved. This method is applicable across a variety of ganglion cell subtypes and is amenable to a wide variety of single-cell physiological techniques.

This article provides a description of how to dissect and record from the isolated retinal preparation in mouse. In particular, we describe how to record light responses from a fluorescently labeled ganglion cell population and subsequently identify and analyze its morphology.

The first steps in vertebrate vision take place when light stimulates the rod and cone photoreceptors of the retina 1.  This information is then ...

Multiple-mouse Neuroanatomical Magnetic Resonance Imaging

The field of mouse phenotyping with magnetic resonance imaging (MRI) is rapidly growing, motivated by the need for improved tools for characterizing and evaluating mouse models of human disease. MRI is an excellent modality for investigating genetically altered animals. It is capable of whole brain coverage, can be used in vivo, and provides multiple contrast mechanisms for investigating different aspects of neuranatomy and physiology. The advent of high-field scanners along with the ability to scan multiple mice simultaneously allows for rapid phenotyping of novel mutations.
Effective mouse MRI studies require attention to many aspects of experiment design. In this article, we will describe general methods to acquire quality images for mouse phenotyping using a system that images mice concurrently in shielded transmit/receive radio frequency (RF) coils in a common magnet (Bock et al., 2003). We focus particularly on anatomical phenotyping, an important and accessible application that has shown a high potential for impact in many mouse models at our imaging centre. Before we can provide the detailed steps to acquire such images, there are important practical considerations for both in vivo brain imaging (Dazai et al., 2004) and ex vivo brain imaging (Spring et al., 2007) that should be noted. These are discussed below.

Magnetic resonance imaging (MRI) has become an increasingly popular tool for examining the phenotype of genetically altered mice. This article illustrates the methods necessary to achieve high-throughput phenotyping of genetically altered mice using multiple-mouse MRI.

The field of mouse phenotyping with magnetic resonance imaging (MRI) is rapidly growing, motivated by the need for improved tools for characterizing and ...

Dissection of a Mouse Eye for a Whole Mount of the Retinal Pigment Epithelium

The retinal pigment epithelium (RPE) lies at the back of the mammalian eye, just under the neural retina, which contains the photoreceptors (rods and cones). The RPE is a monolayer of pigmented cuboidal cells and associates closely with the neural retina just above it. This association makes the RPE of great interest to researchers studying retinal diseases. The RPE is also the site of an in vivo assay of homology-directed DNA repair, the pun assay. The mouse eye is particularly difficult to dissect due to its small size (about 3.5mm in diameter) and its spherical shape. This article demonstrates in detail a procedure for dissection of the eye resulting in a whole mount of the RPE. In this procedure, we show how to work with, rather than against, the spherical structure of the eye. Briefly, the connective tissue, muscle, and optic nerve are removed from the back of the eye. Then, the cornea and lens are removed. Next, strategic cuts are made that result in significant flattening of the remaining tissue. Finally, the neural retina is gently lifted off, revealing an intact RPE, which is still attached to the underlying choroid and sclera. This whole mount can be used to perform the pun assay or for immunohistochemistry or immunofluorescent assessment of the RPE tissue.

A formal demonstration of the dissection of a mouse eye, resulting in a whole mount of the retinal pigment epithelium.

The retinal pigment epithelium (RPE) lies at the back of the mammalian eye, just under the neural retina, which contains the photoreceptors (rods and ...

Wholemount Immunohistochemistry for Revealing Complex Brain Topography

The repeated and well-understood cellular architecture of the cerebellum make it an ideal model system for exploring brain topography. Underlying its relatively uniform cytoarchitecture is a complex array of parasagittal domains of gene and protein expression. The molecular compartmentalization of the cerebellum is mirrored by the anatomical and functional organization of afferent fibers. To fully appreciate the complexity of cerebellar organization we previously refined a wholemount staining approach for high throughput analysis of patterning defects in the mouse cerebellum. This protocol describes in detail the reagents, tools, and practical steps that are useful to successfully reveal protein expression patterns in the adult mouse cerebellum by using wholemount immunostaining. The steps highlighted here demonstrate the utility of this method using the expression of zebrinII/aldolaseC as an example of how the fine topography of the brain can be revealed in its native three-dimensional conformation. Also described are adaptations to the protocol that allow for the visualization of protein expression in afferent projections and large cerebella for comparative studies of molecular topography. To illustrate these applications, data from afferent staining of the rat cerebellum are included.

Neural circuits are topographically organized into functional compartments with specific molecular profiles. Here, we provide the practical and technical steps for revealing global brain topography using a versatile wholemount immunohistochemical staining approach. We demonstrate the utility of the method using the well-understood cytoarchitecture and circuitry of cerebellum.

The repeated and well-understood cellular architecture of the cerebellum make it an ideal model system for exploring brain topography. Underlying its ...

Preparation of Horizontal Slices of Adult Mouse Retina for Electrophysiological Studies

Vertical slice preparations are well established to study circuitry and signal transmission in the adult mammalian retina. The plane of sectioning in these preparations is perpendicular to the retinal surface, making it ideal for the study of radially oriented neurons like photoreceptors and bipolar cells. However, the large dendritic arbors of horizontal cells, wide-field amacrine cells, and ganglion cells are mostly truncated, leaving markedly reduced synaptic activity in these cells. Whereas ganglion cells and displaced amacrine cells can be studied in a whole-mounted preparation of the retina, horizontal cells and amacrine cells located in the inner nuclear layer are only poorly accessible for electrodes in whole retina tissue.
To achieve maximum accessibility and synaptic integrity, we developed a horizontal slice preparation of the mouse retina, and studied signal transmission at the synapse between photoreceptors and horizontal cells. Horizontal sectioning allows&#160;(1) easy and unambiguous visual identification of horizontal cell bodies for electrode targeting, and (2) preservation of the extended horizontal cell dendritic fields, as a prerequisite for intact and functional cone synaptic input to horizontal cell dendrites.
Horizontal cells from horizontal slices exhibited tonic synaptic activity in the dark, and they responded to brief flashes of light with a reduction of inward current and diminished synaptic activity. Immunocytochemical evidence indicates that almost all cones within the dendritic field of a horizontal cell establish synapses with its peripheral dendrites. The horizontal slice preparation is therefore well suited to study the physiological properties of horizontally extended retinal neurons as well as sensory signal transmission and integration across selected synapses.

We developed a horizontal slice preparation of the adult mammalian retina with the plane of sectioning parallel to the retinal surface. Dendritic fields of nonradially oriented retinal neurons were not truncated, allowing the study of signal processing with patch-clamp and imaging techniques.

Vertical slice preparations are well established to study circuitry and signal transmission in the adult mammalian retina. The plane of sectioning in ...

Preparation of Non-human Primate Brain Tissue for Pre-embedding Immunohistochemistry and Electron Microscopy

Despite all the technological advances at the light microscopy&#160;level, electron microscopy remains the only tool in neuroscience to examine and characterize ultrastructural and morphological details of neurons, such as synaptic contacts. Good preservation of brain tissue for electron microscopy can be obtained by rigorous cryo-fixation methods, but these techniques are rather costly and limit the use of immunolabeling, which is crucial to understand the connectivity of identified neuronal systems. Freeze-substitution methods have been developed to allow the combination of cryo-fixation with immunolabeling. However, the reproducibility of these methodological approaches usually relies on costly freezing devices. Moreover, achieving reliable results with this technique is very time-consuming and skill-challenging. Hence, the traditional chemically fixed brain, particularly with acrolein fixative, remains a time-efficient and low-cost method to combine electron microscopy with immunohistochemistry. Here, we provide a reliable experimental protocol using chemical acrolein fixation that leads to the preservation of primate brain tissue and is compatible with pre-embedding immunohistochemistry and transmission electron microscopic examination.

Here, we provide an easy, low-cost, and time-efficient protocol to chemically fix primate brain tissue with acrolein fixative, allowing for long-term preservation that is compatible with pre-embedding immunohistochemistry for transmission electron microscopy.

Despite all the technological advances at the light microscopy&#160;level, electron microscopy remains the only tool in neuroscience to examine and ...

Optical Coherence Tomography: Imaging Mouse Retinal Ganglion Cells In Vivo

Structural changes in the retina are common manifestations of ophthalmic diseases. Optical coherence tomography (OCT) enables their identification in vivo&#8212;rapidly, repetitively, and at a high resolution. This protocol describes OCT imaging in the mouse retina as a powerful tool to study optic neuropathies (OPN). The OCT system is an interferometry-based, non-invasive alternative to common post mortem histological assays. It provides a fast and accurate assessment of retinal thickness, allowing the possibility to track changes, such as retinal thinning or thickening. We present the imaging process and analysis with the example of the Opa1delTTAG mouse line. Three types of scans are proposed, with two quantification methods: standard and homemade calipers. The latter is best for use on the peripapillary retina during radial scans; being more precise, is preferable for analyzing thinner structures. All approaches described here are designed for retinal ganglion cells (RGC) but are easily adaptable to other cell populations. In conclusion, OCT is efficient in mouse model phenotyping and has the potential to be used for the reliable evaluation of therapeutic interventions.

Optical Coherence Tomography: Imaging Mouse Retinal Ganglion Cells In Vivo

This manuscript describes a protocol for the in vivo imaging of the mouse retina with high-resolution spectral domain optical coherence tomography (SD-OCT). It focuses on retinal ganglion cells (RGC) in the peripapillary region, with several scanning and quantifying approaches described.

Structural changes in the retina are common manifestations of ophthalmic diseases. Optical coherence tomography (OCT) enables their identification in ...

Long-Term, Serum-Free Cultivation of Organotypic Mouse Retina Explants with Intact Retinal Pigment Epithelium

In ophthalmic research, there is a strong need for in vitro models of the neuroretina. Here, we present a detailed protocol for organotypic culturing of the mouse neuroretina&#160;with intact retinal pigment epithelium (RPE). Depending on the research question, retinas can be isolated from wild-type animals or from disease models, to study, for instance, diabetic retinopathy or hereditary retinal degeneration. Eyes from early postnatal day 2&#8211;9 animals are enucleated under aseptic conditions. They are partially digested in proteinase K to allow for a detachment of the choroid from the RPE. Under the stereoscope, a small incision is made in the cornea creating two edges from where the choroid and sclera can be gently peeled off from the RPE and neuroretina. The lens is then removed, and the eyecup is cut in four points to give it a four-wedged shape resembling a clover leaf. The tissue is finally transferred in a hanging drop into a cell culture insert holding a polycarbonate culturing membrane. The cultures are then maintained in R16 medium, without serum or antibiotics, under entirely defined conditions, with a medium change every second day.
The procedure described enables the isolation of the retina and the preservation of its normal physiological and histotypic context for culturing periods of at least 2 weeks. These features make organotypic retinal explant cultures an excellent model with high predictive value, for studies into retinal development, disease mechanisms, and electrophysiology, while also enabling pharmacological screening.

The protocol describes organotypic explants of mouse neuroretina, cultivated together with its retinal pigment epithelium (RPE), in R16 defined medium, free of serum and antibiotics. This method is relatively simple to perform, less expensive, and time-consuming when compared to in vivo experiments, and can be adapted to numerous experimental applications.

In ophthalmic research, there is a strong need for in vitro models of the neuroretina. Here, we present a detailed protocol for organotypic culturing of ...