A discrete brown-colored granular reaction for follistatin was detected only in the granulosa layer; the theca interna layer was devoid of staining regardless of follicle type or phase. A day effect (p < 0.001) and a follicle effect (p < 0.001) were detected for absorptive index. A decrease in the staining intensity for the dominant follicle over time (Fig. 6) was reflected in a gradual decrease in the absorptive index (Fig. 4). birth control yasmin
Subordinate follicles displayed a trend similar to that of dominant follicles, but the absorptive index was higher (p < 0.05) for dominant than for subordinate follicles. Heterogeneity values did not differ among days, but they were higher (p < 0.012) in dominant than in subordinate follicles. The follistatin reaction was stronger in the granulosa cells near the antral surface in 4 of 13 growing or early-static phase dominant follicles (Fig. 6) but otherwise appeared to be distributed evenly throughout the granulosa layer. Staining appeared more intense in the perinuclear area of the granulosa cell cytoplasm.
FIG. 4. Intensity (absorptive index, a) and distribution (heterogeneity, b) of follistatin staining (mean ± SEM) measured by densitometric analysis of dominant and subordinate follicles. The data have been arranged to illustrate the growing (D3W1), early-static (D6W1), late-static (D1W2), and regressing (D>17) phases of the dominant follicle of wave 1; preselection follicles of wave 2 one day after wave emergence (D1W2); and follicles of the ovulatory (Ov.) wave during proestrus (D>17). Numbers in parentheses below the x-axis indicate the number of follicles analyzed for each follicle type. Bars with no common letters indicate statistical difference (p < 0.05).
FIG. 5. Intensity (absorptive index, a) and distribution (heterogeneity, b) of follistatin staining (mean ± SEM) measured by densitometric analysis of bovine corpora lutea during metestrus (3 days after ovulation), early diestrus (6 days after ovulation), mid-diestrus (between 9 to 13 days after ovulation), and proestrus (between 17 to 21 days after ovulation) and of regressed corpora lutea of a previous estrous cycle collected between Days 3 and 6 after ovulation. Numbers in parentheses below the x-axis indicate the number of corpora lutea analyzed for each phase. Bars with no common letters indicate statistical difference (p < 0.05).
FIG. 6. Immunohistochemical distribution of follistatin (brown color) in the wall of dominant (a, c, e, g) and subordinate (b, d, f) follicles of wave 1 collected on Day 3 of wave 1 (a, b), Day 6 of wave 1 (c, d), Day 1 of wave 2 (e, f), and Day a 17 after ovulation (g). Note that follistatin staining is confined to the granulosa layer and that a progressive decrease in staining intensity is evident from the growing (a) to the regressing (g) phase. A similar decrease occurred in subordinate follicles. The antral region of the granulosa layer of an early-static follicle has a stronger reaction than the basal region (c). Bar = 50 mm.