Luteal-Hypophyseal Interrelationship in the Rabbit

Abstract

Two-old-day corpora lutea became functional when transplanted into estrous recipient rabbits. Hypophysectomy of the recipients on day 7 after luteal transfer resulted in regression of both the corpora lutea and the follicles when seen 4 days later, and in no recipients were the follicles larger than approximately 0.6 mm. Ovine LH [luteinlzing hormone] (125 [mu]g twice daily) maintained the corpora lutea after hypophysectomy and the follicles were either < 0.8 mm or > 1.5 mm, with none of intermediate size. The corpora lutea regressed, however, if hypophysectomy was combined with either ovariectomy or cauterization of the follicles, even though the LH was continued. Corpora lutea also became functional when transferred into chronically ovariectomized rabbits maintained on 1 [mu]g estradiol-17[beta] daily. When these rabbits were hypophysectomized on day 7 after transfer and the estradiol-170 continued, the corpora lutea were still functional 4 days later. Therefore, LH, in the doses used, is luteo-trophic in rabbits. However, it does not maintain the corpora lutea in the absence of either the follicles or the ovaries unless estrogen also is present.