Identification of the ovulatory follicle in the ewe: associated changes in follicular size, thecal and granulosa cell luteinizing hormone receptors, antral fluid steroids, and circulating hormones during the preovulatory period.

Abstract

The presence of LH receptors in both thecal and granulosa cells appears to be required in preovulatory follicles. Since Finn and Suffolk sheep have significantly different ovulation rates, the number of Graafian follicles with LH receptors in both cell types was investigated to determine the relationship between the number of corpora lutea (CL) per ewe and the number of follicles with LH receptors in both cell types. Follicles with this characteristic LH binding were classified as ovulatory. All other follicles were considered to be nonovulatory. Follicular size, LH/hCG receptor concentrations in thecal and granulose cells, and antral fluid (AF) steroid concentrations were studied in ovulatory and nonovulatory follicles at two periods of the follicular phase of the estrous cycle in Finn and Suffolk sheep. Sheep were studied either before preovulatory gonadotropin surge or during the ascending limb of the preovulatory gonadotropin surge. The mean ovulation rate (2.7 CL per Finn ewe and 1.3 CL per Suffolk e...