Effect of ovine LH on the progesterone content of the granulosa cells in preovulatory follicles of the domestic fowl ( Gallus domesticus )

Laying hens were injected i.v. with a single dose of ovine LH (100 microgram) 6-8 hr after a known ovulation, i.e. when plasma LH concentrations are low. Groups of 4 birds were killed at 15 min intervals up to 1 h after injection and the complete granulosa was obtained from 4 or 5 of the largest preovulatory follicles of each bird for progesterone measurement by g.l.c. Compared with the saline-injected controls which had negligible levels of progesterone, granulosa progesterone increased in all the LH-treated birds. The maximum response (mean progesterone content 1966 ng/follicle) occurred 45 min after injection but there was a significant decline by 60 min. It is concluded that the granulosa cells provide most of the preovulatory plasma progesterone increase.