Maintenance of the corpus luteum during the first trimester of pregnancy is accomplished principally by the secretion of ?

The corpus luteum secretes estrogens, progesterone, and relaxin. hCG, secreted by the syncytiotrophoblast lining the placental villi, maintains the corpus luteum during the first trimester of pregnancy. Antidiuretic hormone (vasopressin does not play a significant role during pregnancy. FSH acts on granulosa cells to promote the conversion of androstenedione to estradiol. LH acts on theca cells to promote androstenedione secretion. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 22. Reproductive Development & Function of the Female Reproductive System. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.