Progestins in Bovine Corpora Lutea, Ovaries, and Adrenals during Pregnancy

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Abstract
Progesterone and [DELTA]4-pregnene-20[beta]-ol-3-one (20 [beta]-ol) were assayed in 89 corpora lutea and 54 pairs of ovaries (corpora lutea removed) and adrenals collected from cows pregnant 16 to 275 days. Levels of the two progestins were significantly higher in corpora lutea from 16 to 89 days (33.6 [mu]g/g) than at 90 to 179 (20.4 [mu]g/g) or after 180 days (27.5 [mu]g/g) of pregnancy. Progesterone per gram of luteal tissue was significantly less at 90 to 179 days (12 ug/g) than after 180 days (18.7 [mu]g/g) or for 16 to 89 days (20.4 [mu]g/g). Progesterone and 20B-ol per gram of luteal tissue were not highly correlated at any stage of pregnancy and the correlation for the study was only 0.21. There was a significant correlation (51 comparisons) between weight of the corpus luteum and ovary weight (r = 0.45) and adrenal (r = 0.30). Corpora lutea were not significantly heavier (P < 0.10) at 16 to 89 days (5.9 g) as compared with 90 to 179 days (5.0 g) or after 180 days (5.5 g). The progesterone content of the ovaries and adrenals was generally less than (1 [mu]g/g) and did not vary significantly during pregnancy. The 20 [beta]-ol level was very low in ovaries and this compound was not positively identified in adrenals. This study suggests that the corpus luteum remains functional throughout pregnancy in the bovine.