Altered steroidogenesis by the fetal bovine freemartin ovary.

Ovaries were taken from 12 freemartins of crown-rump length 4.2-27.5 cm (47-130 days of gestation), 16 singleton fetuses of 5-8 cm (55-75 days) and 18 single fetuses of 10-20 cm (78-108 days). Ovaries were incubated for 24 h in tissue culture Medium 199 supplemented with 5% calf serum. The freemartin ovaries produced 0.16-2.1 ng testosterone/ovary/24h compared with less than 50 pg for normal singleton ovaries. Oestrogen was undetectable n the ovaries (less than 50 pg) of freemartin fetuses of crown-rump length 4.2-9.4 cm (47-77 days), while 16 normal ovaries of the same stage produced 1375 +/- 300 pg/ovary/24 h. The presence of abnormally high amounts of testosterone and the absence of normally occurring oestrogen in the freemartin ovary indicate that the pattern of steroidogenesis in the freemartin is altered as early as 47 days of gestation.