Localization of Acetylcholinesterase in the Neurohypophysis and its Functional Implications. ∗

Summary

Neurohypophyses of 7 cats were stained for AChE activity by AThCh method. In the infundibular stalk, fibers showed light staining, whereas fibers, their vesicular swellings, and terminations showed moderate staining in the infundibular process of the posterior lobe. No significant AChE activity was noted in the anterior or intermediate lobe. Thus, in conjunction with findings of an earlier study (7), neurons of the hypothalamico-neurohypophyseal tract appear to contain light to moderate concentrations of AChE throughout their full lengths. These findings are consistent with previous proposals (7,8) that liberation of endocrine secretions of the neurohypophysis is controlled by liberation of ACh from the same terminals.