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

Progesterone and Atpregnene-20 fl-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 ~g. Progestin concentration per gram was high in the developing corpus luteum on the second and third days of the cycle, but the total quantity was generally less than 100 ~g. until after the sixth day. Maximum quantities were observed at 14-16 days (six cows averaged 251 ~g.). Decline in concentration and total progestins was not marked until near the time of an expected estrus. During pregnancy, the average level for seven cows was 161 ~g. at 25-34 days and for six cows, 250 ~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 four cows 8-22 days post-partum were large (average 46 g.) and contained about four times more progestins than is generally observed (66 ~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 ~g. of progestins in the corpus luteum.