The Gateway to the Brain: Dissecting the Primate Eye

Summary

The non-human primate is an important translational species for our understanding of development and aging. The anatomical organization of the primate retina may provide important insights into normal and pathological conditions in humans.

Abstract

The visual system in humans is considered the gateway to the world and plays a principal role in the plethora of sensory, perceptual and cognitive processes. It is therefore not surprising that quality of vision is tied to quality of life . Despite widespread clinical and basic research surrounding the causes of visual disorders, many forms of visual impairments, such as retinitis pigmentosa and macular degeneration, lack effective treatments. Non-human primates have the closest general features of eye development to that of humans. Not only do they have a similar vascular anatomy, but amongst other mammals, primates have the unique characteristic of having a region in the temporal retina specialized for high visual acuity, the fovea¹. Here we describe a general technique for dissecting the primate retina to provide tissue for retinal histology, immunohistochemistry, laser capture microdissection, as well as light and electron microscopy. With the extended use of the non-human primate as a translational model, our hope is that improved understanding of the retina will provide insights into effective approaches towards attenuating or reversing the negative impact of visual disorders on the quality of life of affected individuals.

Protocol

Part 1: Pre-processing of tissue

1. Tissue should be well perfused with paraformaldehyde, glutaraldehyde, or formalin. This can be achieved through standard transcardial perfusion typically used to harvest other organs. It is recommended that shortly after sacrifice the eyes be injected with fixative just under the lens and stored in fixative.
2. In the present study the subject was deeply sedated with ketamine hydrochloride (10 mg/kg, i.m.), euthanized with an overdose of sodium pentobarbital (25 mg/kg, i.v.) and perfused transcardially with 0.1 M PBS until completely exsanguinated. This is followed by a 4% paraformaldehyde solution in PBS for 5 min ....

Discussion

The preparation of the retina as a wholemount allows for the analysis of the topography and spatial distribution of either the ganglion cell layer or the endothelial cells of the retinal blood vessels³. Quantification of cell density in the periphery of primate retina is readily accomplished. however, in perifoveal and foveal regions, the stacking of multiple layers in the ganglion cell layer obstructs quantification. To circumvent this potential bias, the fovea and perifoveal region can be dissected from the .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Scalpel	Fine Science Tools	10003-12
Scalpel blades	Fine Science Tools	10011-00
Spring scissors	Fine Science Tools	15020-15
Scissors	Fine Science Tools	14090-11	Any surgical scissors are sufficient
Rongeurs	Fine Science Tools	16121-14
Forceps	Fine Science Tools	11027-12
Filter paper	Fisher Scientific	09-924-150
Camel or Sable Hair paintbrush	Any Supplier