Influence of ovarian hormones on formation of solitary cilia and behavior of the centrioles in uterine epithelial cells of the rat

Examination by transmission and scanning electron microscopy of the uterine luminal epithelial cells of rats 3 wk after combined ovariectomy and adrenalectomy revealed the presence of solitary cilia ("9 + 0" type) associated with the diplosome in almost all cells. These were equipped with striated rootlets. Following a single injection of estradiol (0.2 µg/rat sc), solitary cilia were lost in most cells within 12-24 h; at 24 h many of the cells entered mitosis, and none of the dividing cells bore cilia. Some of the stages of ciliary regression are described. Administration of progesterone to the ovariectomized—adrenalectomized rats (5 mg/rat im for 7 days) also resulted in the loss of solitary cilia, and, in addition, brought about a threefold increase in the distance between the two centrioles and a distortion of normal diplosome configuration, so that the centriolar axes were no longer normal to each other. Sequential treatment with progesterone (5 mg/rat for 7 days) and estradiol (0.2 µg/rat, 12 h after last progesterone injection) induced similar changes to those caused by progesterone on its own. It is concluded that (1) the ovarian hormones estradiol and progesterone suppress the formation of solitary cilia by the luminal epithelial cells of the uterus; (2) the solitary cilia are lost before these cells divide in response to estradiol; and (3) progesterone treatment results in diplosomal disarrangement.