Androgen Secretion by the Fetal and Neonatal Rhesus Monkey¹

The capacity of the gonad to produce androgens was studied in the fetal rhesus monkey and data demonstrate that the testes converted 14C-pregnenolone to testosterone (T) and androstenedione (Δ) in vitro.

Abstract

The capacity of the gonad to produce androgens was studied in the fetal rhesus monkey. At approximately days 45 and 60 of fetal life the testes converted 14C-pregnenolone to testosterone (T) and androstenedione (Δ) in vitro. By days 45, 60 and 80 of fetal life, the ovary is relatively quiescent with regard to its ability to synthesize T and Δ from pregnenolone. Measurement of T and Δ in pools of umbilical artery plasma (UAP) and gonads of the monkey at 100, 125 and 150 days of gestation showed more T in plasma from male compared to female fetuses. Δ Concentrations did not differ with fetal sex. Similarly, greater quantities of T were found in the systemic plasma of mothers with male fetuses. During the neonatal period, androgens in the plasma were high on days 1 or 2 but diminished to low levels with time. Fetal testicular tissue contained large quantities of T that fell to low or undetectable amounts in the neonatal period. Ovarian or adrenal tissue contained Δ but no T. These data demonstrate that the fetal testis of the rhesus monkey synthesizes and releases T into the fetal circulation, while the ovary is relatively quiescent in this regard. The significance of these observations is discussed. (Endocrinology87: 680, 1970)