Influence of caffeine administered during pregnancy on the early differentiation of fetal rat ovaries and testes

In this manuscript it is demonstrated that caffeine when administered to the rat (30 mg/kg per day) during pregnancy affected certain aspects of normal sexual differentiation of the fetal gonads. In the male fetus caffeine was shown to significantly inhibit differentiation of the interstitial tissue and Leydig cells. A significant decrease in the number of Leydig cells exhibiting 3β-hydroxysteroid dehydrogenase activity, and consequent reduction in testerone biosynthesis in the fetal testes at day 15 and day 16 of gestation was found. While the beginning of Leydig cell function was first seen in the afternoon of the 14th day of gestation in both the experimental and control groups, the adverse effects became marked by 15 days and extreme by 16 days. With the aid of the scanning electron microscope it was observed that caffeine also had an effect on the earlier morphogenic organisation of the seminiferous cords at 13 days of gestation where the aggregation of the Sertoli cells forming the seminiferous cords, was marginally advanced in the control group. However, the treated group had caught up by 14 days of gestation. In the female fetus scanning electron microscope studies revealed that in the control and caffeine treated groups the early phase of ovarian differentiation and the later 20 day ovaries were similar in morphology, tissue arrangement and overall appearance. It was also seen that chronic caffeine exposure did not affect the rate of early mitotic proliferation of germ cells, nor later in development the numbers entering meiosis. At 20 days of gestation the numbers and proportion of meiotic to atretic oocytes were comparable in the control and treated groups. However, transmission electron microscope studies revealed that caffeine did affect the ultrastructural appearance of the granulosa cells at 20 days of gestation. Throughout the cytoplasm crescent shaped slits or vacuoles repeatedly appeared in the treated group, and were not present in the control group.