下垂体前葉における Corticotrophs と Gonadotrophs とのせり合い

抄録

In approaching the correlation between hypophysial-adrenocortical and hypophysial-gonadal axis by the cytological observation on cellular elements of anterior lobe of pituitary, adult male rats of WISTAR strain were used as 7 experimental groups treated by any of the following procedures or their combinations, as bilateral adrenalectomy, castration, administration of 2.5mg of cortisone, and 0.05mg of testosterone propionate per day. All animals were sacrified as a rule in 14 day. Pituitary glands were fixed with periodic acid SCHIFF's reaction (PAS) or a modified aldehyde fuchsin (AF).
The definite changes destined to occured both in alpha and beta-cells following the bilateral adrenalectomy (c. f. TOMONARI 1957) have almost disappeared 14 days after the operation with the exception of some ectomy-induced signs, i. e. the occurrence of fat droplets either in the cell-body or sinusoidal lumina. 14 days following castration, alpha-cells became somewhat atrophic with the consequent result of decreasing number of both intracellular mitochondria and fine granules. Gonadotrophs provided with a pattern of spherical enlarged cytoplasm which includes a signet-ring, and which usually faintly stained with PAS, showed a marked cell population, especially accumulated in so-called sex zone, and contained expanded signet-rings, whereas thyrotrphs characterized by the condensed protrudent contour whose cytoplasm is strongly stained with PAS decreased pronouncedly in number.
14 days after the adrenalectomy and castration in combination, alpha-cells which tended to be smaller in size increased in number, thyrotrophs, on the contrary, manifested an exaggerated reduction both in number and size. However gonadotrophs increased exclusively in parallel to the proliferation of alpha-cells. Thus, by the simultaneous removal of both glands the degree of the changes in alpha-cell resulted in the intermediary step between those of mere respective ablation, while the alterations in beta-cell resembled in nature those of the castration group.
The consecutive administration of cortisone for 14 days to the castrated rats made alpha-cells degenerative or deteriorative, giving an impression of the cell necrosis, which was, however, less seriously than the consumptive sign of those in intact cortisone administered rats. Gonadotrophs considerably proliferated, hypertrophied and hyperplasied, though they were not so much profound as the castration group; a multiplication of gamma-cells may be responsible for the marked reduction in number of thyrotrophs. These observations would mean the preventing ability of the prior castration from the degeneration caused by the injection of cortisone, and further fairly demonstrate the interference activity of cortisone with the pattern of castration.
Prolonged administration of testosterone for 14 day to the adrenalectomized rats produced the numerous alpha-cells with small size in the anterior lobe. It was of particular remark in this experiment that a lot of gonadotrophs almost disappeared, in spite of the reservation of a few number of thyrotrophs; gammar-cells were also compensatorily proliferated. These may involve in the interferential action between the adrenalectomy and injection of testosterone.
Following the prolonged administration of cortisone and testosterone in combination to the intact rats, alpha-cells usually deteriorated extensively to be resulted in the cell shrinkage and collapse. In all areas of the anterior lobe any healthy beta-cell were not detectable; they were always degenerated and decreased in number, and any cells which is to be apparently identified to gonadotrophs no longer take places; there were only observed a restricted number of thyrotrophs with condensed and hyperchromatic cytoplasm; it was a tendency in this case that gamma-cells did not proliferate but be pycnotic.