Prostaglandin Levels in Peripheral and Follicular Plasma, the Isolated Theca and Granulosa Layers of Pre- and Postovulatory Follicles, and the Myometrium and Mucosa of the Shell Gland (Uterus) during a Midsequence-Oviposition of the Hen (Ga//us domesticus

Prostaglandins (PG) F and E were measured by radioimmunoassay in peripheral, uterine and follicular plasma and in the theca and granulosa layers of the five largest preovulatory and the three largest postovulatory follicles, and in the myometrium and mucosa. Plasma and tissues were collected 16, 12, 8 and 4 h before and immediately after a midsequence oviposition that was accompanied by the next ovulation. PGF concentrations in the peri-pheral and uterine plasma increased at oviposition with a concomitant, 16-fold increase in plasma PGF concen-trations of the largest preovulatory (Fl) follicle. There was a gradual increase in PGF concentrations in the theca layers during follicular maturation, with the large increases occurring 12 h before oviposition in most foll-icles. The highest and the second highest concentrations were observed at oviposition in the Fl and the largest postovulatory (Ri) follicles. In contrast, there were no specific changes in PGF concentrations in the granulosa layers of the follicles in relation to oviposition or follicular maturation. PGE concentrations in the theca layers of the F2 and Fl follicles were greater than in other follicles, while concentrations in the granulosa layer of all the follicles remained low. PGF concentrations in the myometrium and mucosa increased 8 h before oviposition but abruptly decreased at oviposition. These results suggest that the primary source of the increase in plasma PGF at oviposition are the theca layers of the Fl and Ri follicles and that PGs may be involved in uterine contractions for oviposition and in the ovulation process