Apoptosis of the oocytes of hypothyroid neonatal rats

Abstract

Background: The aim of our study was to examine the effect of mild maternal hypothyroidism on the apoptosis of the oocytes in the ovaries of rats in the early postnatal period during formation of oocytes and follicles. Materials and Methods: Hypothyroidism was induced in pregnant and lactating rats by feeding 1.5mg/L propylthiouracil (PTU) through drinking water. Ovaries were obtained from newborns on postnatal day (PND) 0, 4 and 7. The degree of oocyte apoptosis was measured from the largest cross sections (n=2) from each ovary using by Colorimetric - TdT (terminal deoxynucleoid transferase) Enzyme in situ cell death detection kit (Merck). Results: This preliminary result suggests that hypothyroidism induce increase of the total oocyte number from 4. day in the experimental group while the number of apoptotic oocytes is the lowest that day. However, the highest percentage of apoptosis is noticed on day 0. in control group. Conclusion: In our further investigation we will notice whether the morphological changes induced on the oocytes appear before or after development of primordial follicles as a result of the impacts of maternal hypothyroidism on folliculogenesis of their offspring.