THE QUANTITATIVE HISTOCHEMISTRY OF THE RETINA

Abstract

The retina is not only an exceedingly interesting structure in its own right, but it presents an exceptional opportunity for study of the central nervous system, of which it is an integral part. In the retina a number of nervous elements which are usually intimately mixed together have been sorted out into discrete layers. Analysis of each of these layers could provide information as to the composition of several kinds of cell bodies, dendrites, naked axons, and even synapses (in the outer reticular layer) in addition to the rods and cones themselves. Anfinsen measured cholinesterase and DPNl in a number of layers in beef retina (2). Wald isolated the pigment epithelium in the frog and analyzed it for vitamin A and xanthophyll (3). Saito made preparations of outer rod segments by vigorous shaking of retinas in saline, followed by differential centrifugation in strong sucrose or fructose solutions (4). Such preparations have been analyzed for rhodopsin and related substances and for five phosphorus fractions (5). Otherwise, except for preliminary data for MDH and LDH in rabbit retina (6) there do not appear to have been analyses of individual retinal layers. (Some valuable histochemical information has been obtained by staining methods (7-g).) To be reported are analyses of the layers of monkey and rabbit retina by a modified (10) procedure of Linderstr@m-Lang et al. (1 l), which incorporates some of the steps employed by Anfinsen et al. (12). Data for dry weight, total lipides, lactic, malic, and glutamic dehydrogenases, phosphoglucoisomerase, glutamic-aspartic transaminase, and glutamate are reported, as well as the new methods used for measuring some of these.