Histo-morphologic study in fetuses and hormonal changes in fetal fluids during sex differentiation of sheep

This study aimed to investigate histomorphological changes of ovine fetuses along with the levels of the steroid hormones such as progesterone (P4), estradiol (E2), and testosterone (T) in fetal fluids during the sexual differentiation period of genital organs (25-85 days). The initial sex differentiation in these fetuses has occurred on the 35th day of pregnancy. In amniotic fluid, there were significant differences in concentrations of T and E2 between days 25-45 and 46-55 of pregnancy (P = 0.03), and P4 levels between 45 and 65 and 65-85 days of pregnancy (P = 0.02). P4 concentration and P4 to T ratio after the 55th day of pregnancy displayed a significant rise in comparison with their amounts before this time in amniotic fluid (P < 0.05). There was a strong positive association between embryonic age and amniotic fluid P4 concentration and P4/T ratio (P = 0.02). A strong association was registered between the crown-rump length (CRL) and amniotic P4/T ratio (P = 0.02). Furthermore, P4 concentrations in the amniotic fluid of female embryos were higher than sexually undifferentiated embryos (P = 0.06), and amniotic E2 concentration of female embryos was higher than that of males' (P = 0.07). In allantoic fluid, P4 concentrations after the 55th day of pregnancy were higher than its concentrations before the pregnancy (P = 0.05). There was a strong positive association between allantoic P4 and CRL (P = 0.05). Allantoic E2 of female embryos was significantly higher than sexually undifferentiated embryos (P = 0.01). In conclusion, the sexual hormones changed a long time before and after sex differentiation in the amniotic and allantoids fluids. P4 and E2 concentrations were higher in fetal fluids of females than males.