Medroxyprogesterone Acetate: MATERIALS AND METHODS(3)
Ovarian data summary and analyses. A follicular wave was defined as one or more antral follicles that grew from 3 to >5 mm in diameter; the day the follicles were detected at 3 mm was the day of emergence. Groups of follicles emerging within 48 h were included in a wave. The characteristics of ovulatory antral follicles in the last and penultimate follicular waves before ovulation detected after the end of MAP treatment were compared within and between the treatment and control groups by ANOVA (SigmaStat 2.0 for Windows; SPSS Inc., Chicago, IL). Comparisons were not made for the ovulating follicles in preceding waves because none of the control ewes and only three of the seven treated animals had ovulatory follicles that emerged prior to the penultimate wave.
The proportions of ovulatory follicles emerging in the penultimate and final waves before ovulation (follicles growing to >5 mm in diameter) were compared between treated and control ewes by the x2 test (SigmaStat 2.0). The number of ovulations and time at which they occurred, as well as mean numbers of luteal structures per ewe (i.e., CL and luteinized unovulated follicles), were compared between the two groups of ewes by Student t-test (SigmaStat 2.0). Ovulation rates were also compared for the first (immediately before the PGF2„/MAP treatment) and last (after sponge removal in treated ewes) ovulation of the study period, within each group of ewes. Ovulations were observed in MAP-treated ewes during the period of sponging. Therefore, the characteristics of follicles ovulating during MAP treatment in the six treated ewes were noted (i.e., percentage of follicles >5 mm in diameter on the day of PGF2„ that ovulated, day of emergence, maximum follicular diameter, diameter on the day before ovulation, and interval between the attainment of maximum size and ovulation).