PubMed1984
Twenty cyclic gilts were injected im with either saline (control) or 1,000 IU of human chorionic gonadotropin (hCG) on d 12 of the estrous cycle to determine the effects of hCG on follicular development and steroidogenesis. Blood was collected when gilts were sacrificed on d 13 or 16. Follicles were classified as medium (3 to 6 mm in diameter) or large (greater than 6 mm diameter), dissected from the ovary, measured and weighed. Pieces of follicle wall were incubated 3 h in Krebs Ringer bicarbonate buffer (KRB) on ice in an atmosphere of air or at 37 C in an atmosphere of 95% O2:5% CO2. Unconjugated estrogen and progesterone in blood plasma, follicular fluid and 10,000 X g supernatants of incubated follicular tissue homogenates were quantified by radioimmunoassay. On d 13 follicles on ovaries of control or hCG-injected gilts were less than or equal to 6 mm in diameter. On d 16, one of five control gilts had some large follicles, while all five hCG-treated gilts had large as well as medium follicles. On d 16 follicular fluid of large follicles from hCG-injected gilts contained twofold more estrogen and 40-fold more progesterone than medium follicles on the same ovaries. Tissue from large follicles of hCG-injected gilts produced more progesterone in vitro than did tissue from medium follicles (P less than .05), but estrogen production did not differ. On d 16 medium follicles from control or hCG-injected gilts were larger, contained more estrogen and less progesterone than those recovered on d 13 (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)