QUANTITATIVE HISTOCHEMISTRY OF ACETYL‐CHOLINESTERASE IN RAT HIPPOGAMPAL REGION CORRELATED TO HISTOCHEMICAL STAINING

Abstract

Abstract— The quantitative histochemistry of acetylcholinesterase (AChE) has been examined in hippocampus (regio superior) and area dentata. Samples (0–05–2 μg) were dissected from freeze‐dried tissue sections and assayed by either a colorimetric or a radiometric micromethod. In hippocampus the highest AChE activity occurred in a narrow zone just beneath the layer of pyramidal cells. Stratum oriens had a higher activity than stratum radiatum. A small peak of activity occurred in the lacunosal layer. In area dentata the overall activity was about 60 per cent higher than in the hippocampus. The highest activities were found in two zones adjacent to the granular layer. When the results were expressed as activities per volume of tissue they correlated well with microdensitometric measurements on sections stained for AChE by the Koelle method. Following transection of the fimbria the activity decreased to a low level, approaching a common value in the layers examined. The results are discussed in relation to the significance of AChE in the hippocampal region.