The distribution of acetylcholinesterase in the hippocampal formation of the monkey

Abstract

In order to study the distribution of acetylcholinesterase (AChE) in the primate hippocampal formation, we have stained serial sections through the brains of nine macaque monkeys for AChE by two variants of the Koelle acetylthiocholine method. We have found a distinctive pattern of staining in the hippocampal formation which varies in intensity both from region to region, and along rostrocaudal and radial gradients within each region. In the dentate gyrus, there is intense staining of the inner one-third of the molecular layer with much lighter staining in the rest of the molecular layer except for a moderately stained band at its outer edge. In the caudal half of the dentate gyrus, the inner portion of the molecular layer is less intensely stained though there is a distinctly denser band of staining just above, and partly within, the superficial margin of the granule cell layer. The granule cells are unstained but there are AChE-positive fibers which run through the granule cell layer to the molecular layer. The hilar region of the dentate gyrus has a narrow band of heavy staining (which corresponds to an acellular layer in Nissl-stained sections) just subjacent to the granule cell layer; the remainder of the hilus, where most of the hilar cells reside, is less intensely stained and at caudal levels is almost entirely unstained. In the regio inferior of the hippocampus, there is intense staining of the stratum oriens which extends into the pyramidal cell layer; the stratum radiatum and the stratum lacunosum- moleculare are also stained and here the staining pattern shows some degree of stratification. By contrast, most of the alveus, the pyramidal cell somata, and the layer of mossy fibers (stratum lucidum) are unstained. The border region between regio inferior and regio superior of the hippocampus (field CA2 of Lorente de No, '34) is especially heavily stained. This contrasts markedly with regio superior, which is more lightly stained than regio inferior. Stratum oriens and stratum radiatum of regio superior have a more evenly distributed pattern of staining, though the intensity of staining increases sharply at the border with the subiculum. Stratum lacunosum- moleculare is only lightly stained throughout much of the transverse extent of regio superior but there is also a conspicuous and constant patch of heavier staining at the border with the subiculum.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunohistochemical Demonstration of Serotonin-Containing Nerve Fibers in the Mammalian Hippocampal Formation

“…In contrast. Bakst and Amaral [1984) demon strated that the density of AChE-eontaining fibers in the inner one-third of this layer in the monkey was obviously higher than that in the outer two-thirds. In addition.…”

Hippocampus and Dentate Area of the European Hedgehog

“…In guinea pigs, the superficial third of the layer stains very intensely, whereas the widest, intermediate part stains only weakly. Still other patterns of lamination have been observed in the dentate areas of ferrets [10], cats [27], macaque monkeys [1,31] and humans [23]. Only in mice [30] has a staining pattern been observed that roughly seems to correspond to that found in European hedgehogs.…”

Distribution of Choline Acetyltransferase Immunoreactivity in the Telencephalon of the Lizard <i>Gekko gecko</i>

“…It seems likely that the distribution of cholinergic elements in the medial cortex in reptiles is species-specific [Re gidor and Poch, 1988]. A comparable hypothesis has been put forth for the dentate area in mammals [Bakst and Amaral, 1984;Geneser, 1987],…”