Progestins in Corpora Lutea, Ovaries, and Adrenals After Estrus and Breeding of Normal and Abnormal Cows

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Abstract
Progesterone and [image]4-pregnene-20 [beta]-ol-3-one (progestins) were separately determined in the corpus luteum, ovaries, and adrenals. A total of 77 animals was studied and 53 were considered reproductively normal at the time of slaughter. Progestin content of the corpus albicans prior to ovulation ranged from 0 to 24 [mu]g. Progestin concentration per gram was high in the developing corpus luteum on the 2d and 3d days of the cycle, but the total quantity was generally less than 100 [mu]g until after the 6th day. Maximum quantities were observed at 14-16 days (6 cows averaged 251 [mu]g). Decline in concentration and total progestins was not marked until near the time of an expected estrus. During pregnancy, the average level for 7 cows was 161 [mu]g at 25-34 days and for 6 cows, 250 [mu]g at 37-42 days. The differences were also reflected in concentration, since the weight of the corpus luteum was, on the average, essentially constant. Neither size nor progestin content of the ovaries and adrenals varied appreciably among these cows. Adrenals of 4 cows 8-22 days post-partum were large (average 46 g) and contained about 4 times more progestins than is generally observed (66 [mu]g). The progestin content of the corpus luteum of repeat breeders was not unlike normal animals in a similar stage of the estrous cycle. The corpora lutea and fluids from cystic follicles generally had less progestins than luteal cysts or the fluid they contained. One cow with a dead embryo at 20 days postbreeding had only 8 [mu]g of progestins in the corpus luteum.