Introduction. The ovarian surface epithelium (OSE) undergoes intensive regeneration and remodeling after each ovulation during the whole reproductive period. This process increases the risk of one of the most common ovarian tumors in women and the female dog. Considering the fact that maternal hypothyroidism highly impacts cell proliferation and cell death during folliculogenesis in the early neonatal period, we aimed to analyze its effect on OSE morphology and dynamics. Materials and Methods. The study was performed on newborn (24-h-old) and neonatal (4-day-old) female rats, a randomized trial between the control and hypothyroid groups, born under controlled circumstances and hypothyroid mothers, respectively. Their ovaries were analyzed histologically and processed to determine the OSE cell height as an average value of four measurement points. Also, the immunopositivity of the proliferating cell nuclear antigen (PCNA) and caspase-3 were assessed semiquantitatively. Results and Conclusions. No major structural differences of OSE were found between groups within the given ages except for a slight increment of OSE cell height and incompleteness of apical cell membrane with cytoplasmic projections in hypothyroid animals. PCNA immunopositivity of the OSE cells was higher in ovaries of hypothyroid animals of both ages in comparison to the controls. Moreover, only scarce OSE cells were caspase-3 positive in both groups and ages, with no difference in immunopositivity. Our study confirms the impact of hypothyroidism in the early postnatal period on morphology and proliferation rate of OSE cells, with no effect on caspase-3 dependent cell removal, which may serve as a premise for future investigation of potential carcinogenesis, in terms of prevention and treatment of ovarian cancer.
Proliferating Cell Nuclear Antigen Immunoreactivity in the Ovarian Surface Epithelium of Mice of Varying Ages and Total Lifetime Ovulation Number Following Ovulation1