Follicular atresia and LH concentrations during the follicular phase of the estrous cycle in the goat (Capra hircus).

Abstract

The objective of the study was to identify the effects of LH on the final follicle maturation process as well as the incidence of atresia during the follicular phase of the goat's estrous cycle. In Experiment 1, concentrations of the LH were measured during the follicular phase of a synchronized cycle in 8 Canary goats. In Experiment 2, the same animals were synchronized again. On each day of a 4-day experimental period (day 0 = day of sponges withdrawal), 2 of the goats were bilaterally ovariectomized. Follicles with a diameter > 1 mm were dissected out to obtain qualitative histological data in normal, early atretic I, early atretic II, advanced atretic I and advanced atretic II follicles. The total interval from sponge withdrawal to LH peak was 77.5 +/- 9.8 h. LH peak concentration averaged 44 +/- 5.3 ng/ml and the mean length of the preovulatory surge (amounts over 10 ng/ml) was 8.9 +/- 0.9 h. During the total follicular phase, there were more atretic follicles than normal follicles (58 vs. 30, P < 0.05). The number of early and advanced atretic follicles was similar. There were more early atresia I than early atresia II follicles (23 vs. 6, P < 0.05). On day 2, the number of advanced atretic follicles was greater than early atretic follicles (10 vs. 4, P < 0.05). There was an increase in the number of early atretic follicles from day 2 to day 4 (4 vs. 9, P < 0.05), which was consistent with the effects of the preovulatory LH surge.