Author(s): Jun-Qian Liu, Takanori Miki, Katsuhiko Warita, Ken-ichi Ohta, Tomiko Yakura, Yoshiki Ma-tsumoto, Yoshiki Takeuchi
Synaptic structures of neuronal contacts with pituicytes in the posterior pituitary (PP) were investigated in detail after wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) injection into the rat hypothalamus including the paraventricular, dorsome-dial and arcuate nuclei. The injection resulted in heavy labeling of hypothalamic fibers in the PP. In the neuropil of the PP, there were a lot of terminals containing HRP-reaction product (RP) recognized as electron dense lysosomal-like structures. It was of particular in-terest that the terminals make synaptic contacts with pituicytes. Although the neuronal con-tacts were characterized by the structure of presynaptic thickening, occasionally two classes could be distinguished - asymmetrical and symmetrical synaptic contacts (Gray’s type I and II). These findings provided the morphological evidence for tight structural relationship of neurons with pituicytes in the PP, as well as neuro-neuronal connections in the central nerv-ous system, and additionally for pituicyte modulation of neurohormone output.