Progesterone secretion during pregnancy in sheep with an autotransplanted adrenal and an autotransplanted ovary.

Secretion rates by the major sites of progesterone synthesis were measured during pregnancy in 3 ewes with single fetuses after autotransplantation of the left adrenal and the left ovary (containing the corpus luteum) to the neck. The total production of progesterone measured by tracer kinetics increased from 12.1 +/- 2.0 (s.e.m.) to 31.3 +/- 2.4 microgram/min between 66--103 and 133--145 days p.c. Ovarian and adrenal secretion rates measured directly at the same times decreased from 5.2 +/- 0.9 to 2.1 +/- 0.9 microgram/min (ovary), or remained unchanged, about 0.03 microgrom/min (adrenal). The difference between the total production of progesterone and ovarian and adrenal secretion showed that the contribution from other endocrine tissues (presumably the placenta) increased from 6.8 +/- 1.5 to 29.2 +/- 4.1 microgram/min (P less than 0.001) during this period.