Morphogenic change in the cervix of the ewe after prolonged exposure to oestradiol-17

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Abstract
This study examined the effects of prolonged exposure to oestradiol-17.beta. on the morphology of the cervix of the ewe. Merino ewe lambs were implanted subcutaneously with 3 Silastic capsules which released a total of approximately 300 .mu.g oestradiol-17.beta. per day. After exposure for 200 days the uterus was more markedly bicornuate, and the cervix was broader and softer, than in controls. The cervical folds were shorter and contained many stromal cells. The amount of lamina propria under the folds was increased and altered so that it contained tubular glands and more stromal cells. The endocervix thus came to resemble endometrium. This appearance developed within 80 days of exposure, and remained for at least 170 days after implant removal. In a second experiment, mature multiparous Merino ewes were ovariectomized and implanted with 1, 2 or 4 similar oestradiol capsules for 140 days. Similar features developed in these ewes, and the degree of change was almost as great with 1 implant as with 4. Changes of a similar nature can be produced in other species by oestrogen given during organogenesis but not during adult life. The changes indicate that the ewe has an ability to display a degree of morphogenic response to oestradiol during adult life.