Freeze-fracture replica studies of effects of ACTH treatment and hypophysectomy on the cell surface of the rat adrenal inner cortex.

The morphological change of the cell surface in the inner zone of the adrenal cortex was studied in intact, hypophysectomized, and ACTH-treated hypophysectomized rats, using freeze-fracture replicas. In both intact and hypophysectomized ACTH-treated animals, the P fracture face of the plasma membranes of the cortical cells facing capillaries shows groups of characteristic finger-shaped microvilli, which arise horizontally from the edges of a small cavity on the cell surface to form various configurations ranging from incompletely organized, flower bud-like to complicated, arboraceous ones. In the non-treated hypophysectomized animals, however, the microvilli in such groups decrease in number and shorten in length but increase in width, looking like a blade of a prickly-pear cactus or an irregular-shaped plate. On the other hand, presumptive exocytotic and endocytotic specializations of intra-membraneous and experimental animals.