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Characteristics of the uterus anc cervix after ovariectomy of ewes with permanent phytooestrogen infertility (PPI) were compared with controls. Ewes with PPI had more oestrogen-binding sites in the cervix, but not in the uterus. There was no difference between the two groups of ewes in the binding affinity constant of receptors from the uterus or cervix. There were more keratinized cells in the vaginal epithelium of ewes with PPI, and the rates of protein and glycoprotein synthesis in the uterus and cervix were higher in ewes with PPI. These results offer further evidence that PPI in adult ewes is similar to the "persistent oestrus' syndrome in rodents oestrogenized neonatally.

The amount of cervical mucus recovered from control ovariectomized ewes increased with increasing doses of oestradiol benzoate (OB), while the maximum Spinnbarkeit of mucus occurred at an intermediate dose of OB. Neither the amount nor the Spinnbarkeit of mucus varied with the dose of OB in ewes with permanent infertility caused by grazing oestrogenic pasture (clover-affected ewes). Furthermore, the increase in Spinnbarkeit of cervical mucus seen in normal ewes treated over a 3-day period with OB or with implants containing oestradiol did not occur in affected ewes. In control ewes treated repeatedly with OB, production of mucus declined within 5 days, but no change in secretion was detectable in clover-affected ewes. Therefore, neither the amount nor the duration of oestrogenic stimulation affected the cervical mucus in ewes with clover disease. Affected ewes produced more mucus than did controls in the absence of oestrogenic stimulation. It is concluded that the relatively normal volume of mucus in affected ewes treated with OB results largely from autonomous production. The Spinnbarkeit does not increase in these ewes because the ability of the cervix to respond to oestrogen is impaired.

Functional abnormalities have been observed previously in the oestrogen-responsive tissues of ovariectomized ewes with permanent infertility resulting from prolonged exposure to oestrogenic pastures. In the present study, such ewes had higher rates of protein and glycoprotein synthesis in the cervix and uterus than control ewes, but the number of oestradiol-17 beta receptors in the nucleus was similar in each group. After treatment with oestradiol-17 beta, the increase in synthesis of protein and glycoprotein in the uterus and cervix was less in clover-affected ewes, but the amount of oestradiol-17 beta-receptor complex in the nucleus of uterine cells 6 h after ewes were injected with oestradiol-17 beta was similar in clover-affected and control ewes. The rate of replenishment of oestradiol-17 beta receptors in the cytoplasm at 24 and 48 h after oestradiol-17 beta injection was also similar in both groups. The abnormal function seen in the genital tract of clover-affected ewes could not, therefore, be shown to depend on changes in oestradiol-17 beta receptors.