THE STUDIES OF THYMUS INVOLUTION IN MICE INDUCED BY ESTRADIOL / 解剖学报

ABSTRACT

The involution of female Swiss mouse thymus induced by estradiol (Es_2) were studied by morphological methods.The involuting thymuses of 2-month-old mice increased greatly in weight after ovariectomy. Treated with Es_2, the thymuses of immature mice not only stopped growing, and also involuted apparently. The regeneration of thymuses was impeded in the mice whose thymuses had already involuted induced by hydrocortisone when treated with Es_2. These results proved the obvious inhibiting and involution-inducing effects of Es_2 on thymus. The pattern of the thymus involution induced by Es_2 was different from that by hydrocortisone. Es_2 had no lethal effect on thymocytes either in vivo or in vitro, but it reduced the proliferative rate of thymocytes slowly and caused the thymus involution gradually. Es_2 made no remarkable changes in weight and histology of adrenal glands. Thymus involution induced by Es_2 was also detected in adrenalectomized mice. These results indicated that thymus involution induced by Es_2 was adrenal independent. Accompanying the thymus involution, the number of type Ⅰ thymic epithelial cells decreased, which were considered to produce thymic hormones actively, and the structure of thymic epithelial cells denatured. These morphological degenerative alterations suggest that Es_2 can result in some changes or decline of the hormone secretory activity of thymic epithelial cells, and then the proliferation of thymocytes will reduce and thymus involution will take place.