Effect of successive enucleations of bovine corpora lutea on formation and function of subsequent luteal tissue.

I T has been demonstrated that exogenous progesterone exerts a stimulatory effect on ovulation in cattle (Hansel and Trimberger, 1952) as well as an inhibitory effect (Ulberg, Christian and Casida, 1951; Trimberger and Hansel, 1955; Nellor and Cole, 1957; Labhsetwar et al., 1964). However, the role of endogenous luteal progesterone in the regulation of bovine corpus luteum formation and functional activity is conjectural. The present study was conducted to determine the effect of endogenous luteal progesterone withdrawal, as achieved by successive enucleations of bovine corpora lutea, on (1) the formation of subsequent corpora lutea as determined by gross morphology and luteal tissue weight and (2) the functional activity of subsequent luteal tissue as estimated by initial progesterone concentration and de novo progesterone production during in vitro incubation.