Sahu A, Maiti B R
Exp Clin Endocrinol. 1984 Oct;84(2):203-10. doi: 10.1055/s-0029-1210388.
The effects of long-term administration of norethisterone, a progestogen-only contraceptive, at a dose of 0.5 mg/rat daily for 75 days, were evaluated in the ovary of cycling rats using histomorphic and karyokinetic (by colchicine technique) techniques. Norethisterone induced follicular atresia, decreased the number of normal follicular population and altered the appearance of the interstitial gland. Atresia was markedly noticed particularly in the follicles less than 200 micron in diameter. In addition, fresh or old corpora lutea were not found in the ovary. Simultaneously the progestin also stimulated the mitotic activity in the granulosa and theca of the normal follicles, especially of 201-300 micron in diameter. The findings suggest that norethisterone causes antifertility mainly by preventing follicular development and inducing atresia, thereby inhibiting perhaps ovulation.
采用组织形态学和细胞动力学（秋水仙素技术）方法，对处于发情周期的大鼠卵巢进行研究，以评估长期每日给大鼠注射0.5毫克炔诺酮（一种仅含孕激素的避孕药），持续75天的效果。炔诺酮可导致卵泡闭锁，减少正常卵泡数量，并改变间质腺外观。闭锁现象在直径小于200微米的卵泡中尤为明显。此外，在卵巢中未发现新鲜或陈旧的黄体。同时，该孕激素还刺激了正常卵泡（尤其是直径为201 - 300微米的卵泡）颗粒层和卵泡膜的有丝分裂活性。研究结果表明，炔诺酮主要通过阻止卵泡发育和诱导闭锁来发挥抗生育作用，从而可能抑制排卵。
