Testosterone, progesterone, estradiol-17β, prostaglandin F (PGF) and E (PGE) secretion were measured by radioimmunoassay in cultured early, bovine fetal ovaries (n = 40) and testes (n = 62) from preimplantation age (32–35 days, 1.8–2.5 crown-rump, C-R length) and postimplantation embryos (age 36–85 days, 2.6–12.4 cm C-R length). First measurable amounts of estradiol-17β secreted by ovaries and testosterone by testes were found in gonads of 3.3 cm C-R length (approximately 42 days of age). The range of mean values of the different age groups for testosterone secretion by testes was 0.39–2.33 ng/testis/24 h. Estradiol-17β secretion by ovaries ranged from 1.16–2.22 ng/ovary/24 h for the 3.3–8.0 cm C-R length, but was undetectable for the 8.1–12.4 cm length groups. Testosterone and estradiol-17β secretion by the cultured testes and ovaries were unmeasurable, (<50 pg/gonad/24 h) before morphological sex differentiation becomes apparent (32–42 days). Measurable amounts of progesterone (0.20–2.12 ng/gonad/24 h) were secreted by both cultured testes and ovaries in all age groups studied and concentration increased with age. Both PGE and PGF were secreted by the cultured testes and ovaries throughout the whole period studied. Addition of bovine LH to cultured testes significantly enhanced the secretion of testosterone by testes for all age groups greater than 3.3 cm C-R length, whereas significant enhancement of estradiol-17β secretion by ovaries was found only at 3.3–4.1 C-R length. The high levels of testosterone produced by testes and estradiol-17β by ovaries in 45 ± 3 day gonads suggest that bovine embryonic gonads are not only morphologically, but also functionally differentiated by this time. The findings clearly show that steroidogenesis beyond progesterone synthesis occurs in bovine fetal ovaries.
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Shemesh et al. (1978) studied this question.