Skip to main content
ARS Home » Research » Publications at this Location » Publication #64401
Title: FOLLICULAR ATRESIA, FOLLICULAR FLUID HORMONES, AND CIRCULATING GONADOTROPINS DURING THE MID-LUTEAL PHASE OF THE ESTROUS CYCLE IN PIGS

Author
item Guthrie, Howard
item Cooper, Bruce

Submitted to: Biology of Reproduction
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Reproductive efficiency in the pig is heavily dependent upon the number and fertilizability of follicular oocytes. Of great importance to the swine industry is a better understanding of the changes which occur in follicular growth patterns during the luteal phase of the estrous cycle. The purpose of this study was to determine whether there was any evidence for waves of follicular growth and atresia (death) between days 7 and 15 of the estrous cycle. The incidence of atretic follicles was 35% and while individual animal values ranged from 12 to 70 %, mean values did not differ among days of the cycle. Changes in follicular steroid concentrations and granulosa cell apoptosis were not associated with changes in concentration of plasma hormones. These results support the notion of continuous development of antral follicles without discernable waves of growth and atresia. This knowledge may influence the design of technologies used by scientists and producers to regulate follicular growth and oocyte maturation.

Technical Abstract: The purpose of this study was to determine whether there was any evidence for waves of follicular growth and atresia during the luteal phase of the estrous cycle. Pigs were slaughtered on days 7, 9, 11, 13 and 15. Apoptotic (Ao) granulosa cells were those containing sub-diploid DNA fluorescence as determined by flow cytometry. Follicles were classified atretic with greater than 10% or nonatretic with less than 10% Ao granulosa cells. The percentage of atretic follicles per pig was 35.5. The mean %Ao granulosa cells was greater in atretic (28.6 +/- 2.3) than in nonatretic (3.6 +/- .3 follicles, but means did not differ among days. Follicular estradiol concentration was less in atretic than nonatretic follicles. Even in nonatretic follicles, overall steroidogenesis was low during the luteal phase of the estrous cycle. Progesterone concentration was greater in atretic than in nonatretic follicles. Changes in follicular steroid concentration and granulosa cell apoptosis were not associated with change in plasma hormone concentration. These results support the notion of continuous development of antral follicles without discernable waves of growth and atresia.