Effects of prenatal dexamethasone on fetal rat ovary

Abstract

Glucocorticoids affect the growth and maturation of fetal organ systems, but overexposure to exogenous glucocorticoids retard fetal growth and may alter developmental process in sensitive tissues. On the other hand, fetal ovary is not characterized by definitive follicular structure, but the clusters of germinative cells are predominant. Germ cells may be in meiotic prophase or with sign of degeneration.

The aim of this study was to determine whether prenatal exposure to dexamethasone (Dx) altered normal structure and development of ovary in 19 day old rat fetuses. Pregnant females in the experimental group received subcutaneous injections of 1.0, 0.5 and 0.5 mg Dx /kg body weight on days 16–18 of pregnancy. Control mothers were injected with the same amount of saline. On day 19 of pregnancy, the dams and their fetuses were sacrificed under ether anesthesia and the fetuses were referred to as 19-day-old fetuses. Fetal ovaries were prepared for further stereological examination.

The volume of the fetal ovary estimated using Cavalieri’s principle was significantly reduced after exposure to Dx by 22% (P<0.05) in comparison with control ovary. Using a fractionator-physical disector method, a reduction in total number of germ cells in meiotic prophase by 43% (P<0.05) was observed, while total number of germ cells with sign of degeneration increased by 54% (P<0.05), when compared with control values.

Overexposure to dexamethasone during fetal development intensifies the process of degeneration of germ cells in the ovary, contributing thus the reduction of reproductive potential for the individual.