Steroid biosynthesis by gonads of 7- and 10-day-old chick embryos

Testes, left ovaries, and rudimentary right ovaries from 7- and 10-day-old chick embryos were incubated for 30 min with progesterone as a precursor.20α-Dihydroprogesterone, 20β-dihydroprogesterone, 17α-hydroxyprogesterone, androstenedione, and testosterone were synthesized by left ovaries and testes of 7- and 10-day-old chick embryos. Moreover, the ovaries produced estradiol-17β and estrone at both ages studied.Between 7 and 10 days, testes and left ovaries showed an important increase in steroidogenic capability. At 7 days of embryonic life, both gonads produced 20β-dihydroprogesterone as the major progesterone metabolite. At 10 days, 17α-hydroxyprogesterone was preferentially formed.Rudimentary right ovaries synthesized 17α-hydroxyprogesterone, androstenedione, 20α-dihydroprogesterone, and 20β-dihydroprogesterone at 7 days of maturation. At 10 days of development, testosterone and estradiol-17β were also detected. 20β-Dihydroprogesterone was the principal metabolite identified at both stages of development of this rudimentary gonad.