THE PROGESTERONE CONTENT OF THE GUINEA-PIG CORPUS LUTEUM DURING THE REPRODUCTIVE CYCLE AND AFTER HYSTERECTOMY

Abstract

SUMMARY Progesterone in the corpora lutea of unmated, pregnant and hysterectomized guinea-pigs was assayed chromatographically using a modification of the procedure described by Short [1958b]. Its concentration on the 6th day after ovulation was similar in unmated and pregnant animals. By the 11th to 13th day the concentration in non-pregnant animals had decreased by one-half, but in the pregnant animals the amount was unchanged. A two- to threefold increase occurred between the 11th to 13th and the 21st to 23rd day which, it is suggested, coincides with the production of a luteotrophin. Throughout the remainder of pregnancy the concentration of progesterone in the corpus luteum was maintained at a high level. The results are compared with those that have been obtained in other species. A very high concentration of progesterone was found in the corpora lutea of hysterectomized guinea-pigs. The use of this experimental animal is suggested for further work on the hormonal control of the life-span of the corpus luteum.