ENDOCRINE DIFFERENTIATION OF THE XY SEX-REVERSED MOUSE OVARY DURING POSTNATAL-DEVELOPMENT

When the mouse Y chromosome of Mus musculus domesticus is placed onto the C57BL/6J genetic background, half of the XY progeny develop bilate ral ovaries and the female phenotype, but lack regular estrous cyclici ty and lose embryos after fertilization. In the present study, we comp ared the endocrinological activity of XY ovaries with XX ovaries durin g postnatal development by measuring steroids in the incubation medium by radioimmunoassay. At 1 day postpartum (d.p.p.), production of prog esterone and estradiol was significant while testosterone was undetect able in both ovaries. At 14 and 35 d.p.p., amounts of testosterone and estradiol produced by XY ovaries were half of those by XX ovaries. Pr oduction of progesterone by XY ovaries was slightly higher than XX ova ries at 14 d.p.p., but only half of that at 35 d.p.p. Addition of gona dotropins increased testosterone production by XX ovaries but not by X Y ovaries at either 14 or 35 d.p.p. Progesterone production in XY ovar ies at 35 d.p.p. was increased by gonadotropins to a much lesser exten t than in XX ovaries. Gonadotropins increased estradiol production sim ilarly in both ovaries at 35 d.p.p. Striking differences were found in the histochemical distribution of 3beta-hydroxysteroid dehydrogenase between XY and XX ovaries at 14, but not at 35 d.p.p. In conclusion, t he XY ovary develops abnormal endocrine features during the postnatal period, which likely lead to the fertility problems at puberty.