Effect of cycloheximide on the ovine corpus luteum: the role of granules in the secretion of progesterone.

Cycloheximide (3 mg/h) was infused into the corpus luteum of the sheep via a side branch of the ovarian artery. The concentration of progesterone in the peripheral plasma and the luteal tissue decreased after the infusion. Ultrastructural studies showed that cycloheximide caused inhibition of the formation and secretion of densely stained granules in the luteal cells. The results provide further evidence that progesterone bound to protein is secreted by the luteal cell in the form of granules.