Ultrastructural localization of the cholinesterase (ChE) activity was examined in the interventricular septum of the guinea pig heart using the Karnovsky's method. Beneath the endocardium nerve fibers, mostly of nonmyelinated type, were found entering into the intermuscular space. Two or more preterminal axons were found enclosed within a Schwann cell, although some were naked or incompletely covered. Terminal axons were observed near or within the specialized cardiac muscle cells of the conduction system and also adjacent to the ordinary myocardial cells. In preterminal axons and nerve bundles the final reaction product showing the ChE activity was found in the axon-Schwann interspace, the interspace between neighboring axons and corresponding plasma membranes of the area. In terminals the enzymatic activity was found in the interspace between axolemma and sarcolemma, the axon-Schwann interspace and plasma membranes of enzymatically positive areas.
No takes yet. Share an insight, caveat, or question.
Hirano et al. (1967) studied this question.