ALDEHYDE-FUCHSIN POSITIVE MATERIAL IN BRAIN OF SQUIRREL MONKEY (SAIMIRI SCIUREUS).

Abstract

AbstractIn the squirrel monkey, nerve cells in certain areas of the brain are characterized by abundant granules which stain intensely with aldehyde‐fuchsin but not with chromium hematoxylin.These cells fall into three main types: Type A, with a polar clumping of the granules, characterize the region surrounding the stria terminalis in the amygdala and the supratrochlear nucleus of the mid‐brain. Type B, which have a heavy diffuse granulation, are found in the lateral and caudal hypothalamus and in nucleus raphes ventralis. Less heavily granulated cells classified as Type C distinguish the entire nucleus subthalamicus, and are prominent in nucleus septalis triangularis, rostral midline thalamus, and area CA2 of the rostral hippocampus. Cells of these corresponding types and distribution are not seen in the brains of cat, rat and mouse.The cerebellum and pineal body contain extracellular material which stains with aldehyde‐fuchsin but not chromium hematoxylin.The granules of the nerve cells stain with PAS, Sudan black B, and oil red O, suggesting that they have carbohydrate and lipid components.As in other species, the neurosecretory substance of the paraventricular and supraoptic nuclei is stained both by aldehyde‐fuchsin and chromium hematoxylin. Material showing a positive reaction to both these stains is also found in the glia of the nucleus septalis triangularis, subfornical organ, lateral hypothalamus, and locus caeruleus. All these regions, except the lateral hypothalamus, show similarly staining material in the extracellular spaces.Of anatomical interest is the close association of the aldehyde‐fuchsin positive neurons with phylogenetically ancient cellular structures and fiber systems of the brain. In the squirrel monkey they would seem to provide a basis for further characterization of certain nuclei and a new division of the amygdala.