Mitotic Activity in the Adenohypophysis of Pregnant and Lactating Rabbits

Abstract

Summary.

Formation and release of secretory granules during mitosis in the anterior pituitary gland.

“…This finding might support the notion that the fully differentiated cells lose the ability to divide through mitosis (HEIDENHAIN, 1911;RUSCH, 1954). However, many reports have been published indicating the possibility to undergo mitosis for well differentiated cells of various types of tissues such as adenohypophyseal cells (ALLANSON et al, 1969;KUROSUMI and KOBAYASHI, 1966;ZAMBRANO and DEIS, 1970;KUROSUMI, 1971), pancreatic islets (LIKE and CHICK, 1969), smooth muscle cells (COBB and BENNETT, 1970), parotid gland (REDMAN and SREEBNY, 1970), non-neoplastic melanocytes (JIMBOW et al, 1975) and thyroid follicular cells (ZELIGS and WOLLMAN, 1979).…”

“…In the adenohypophysis, however, some researchers as a result of light microscopy have been aware of the fact that fully differentiated secretory cells may multiply through mitosis (ALLANSON et al, 1969). By electron microscopy KUROSUMI and KOBAYASHI (1966) in ACTH cells and ZAMBRANO and DEIS (1970) in prolactin cells demonstrated mitotic figures in the cells containing secretory granules.…”

Secretory and mitotic response of the male rat pituitary gland to repeated doses of oestrogen

“…The other half was fixed in BouinHollande solution and 5-mp thick sections were cut and stained with haematoxylin and eosin. The cells in mitosis in the anterior lobe were counted in one section of each half pituitary gland and the number expressed as rnitoses/mm2 using the method of Allanson et al (1969) to estimate area of the section. The testes and adrenal glands were removed from each rat and weighed.…”

Effects of Stilboestrol on Growth Hormone Secretion and Pituitary Cell Proliferation in the Male Rat

“…The cells in mitosis in the anterior lobe were counted in one section of each half pituitary gland and the number expressed as mitoses/mm2. The area of anterior lobe in each section was determined by the method of weighing paper cut to the outline of the anterior lobe in a projected image of the section of known magnification and comparing this with the weight of paper of known area (Allanson, Foster & Cameron, 1969). The product of mitotic index (mitoses/mm2 of anterior lobe section) and whole pituitary weight provides a very approximate estimate of total mitotic activity in the anterior lobe.…”