| In recent years, a substantial amount of SP, CGRP and galanin-immunoreactive nerve fibers were identified in the anterior pituitary (AP) of several mammalian species including human in our laboratory, by using immunocytochemical method. The peptidergic nerve fibers were found to be in close relationship with AP gland cells, and even make typical synaptic contacts with them, thus their motor nature were established morphologically. These peptidergic nerve fibers originated, at least in part, from the hypothalamus. Moreover, these fibers could respound actively to the different endocrine status. Recent in vitro studies showed that excitation of the nerve fibers in the AP by applying electrical field stimulation could affect the secretion of AP hormones, indicating a direct neural regulation of the secretion of AP gland cells. The part of Harris' theory, that the AP does not receive a direct innervation was thus challenged. A hypothesis of neural-humoral dual regulation of the AP of the mammals was presented by Professor Ju et aLAccording to this hypothesis, a considerable amount of nerve fibers are located in the AP of the mammal. They are in close relationship with the AP gland cells and make synaptic contacts with them. The secretion of the AP gland cells can be modulated by both humoral and neural factors. The nervous elements may exert fast regulation of AP gland cells, presumably more important under some physiological status, such as stress.There still remain some problems on the morphological studies of the innervation of AP of mammals, such as the origin of the innervation; the changes of the nerve fibers during ontogeny and hormone manipulations. The presence of a large amount of small clear vesicles in the SP or CGRP-immunoreactive nerve terminals, suggest the existence of classical neurotransmitters, their relationship, however, with AP...
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