Z-cells and oogonia/oocytes in the advanced process of autophagy are the dominant altered cells in the ovaries of hypothyroid newborn rats
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Induced prenatal hypothyroidism in rat pups leads to accelerated primordial follicle assembly and premature follicular atresia with ovary failure. This work investigates the influence of maternal hypothyroidism induced with 6-n-propyl-2-thyouracil (PTU) on the number and morphology of oogonia/oocytes in newborn rat pups with light and transmission electron microscopy. Expression of apoptosis and autophagy markers in oogonia/oocytes were examined using immunohistochemistry. Hypothyroid newborn pups had a decreased number of mitotic and resting oogonia, while the number of altered oogonia/oocytes was increased. Ultrastructural observations revealed the increased presence of degenerated pachytene oocytes (Z-cells) and oogonia/oocytes undergoing autophagy, apoptosis and combined apoptosis and autophagy, in this group. The most abundant altered oogonia/oocytes in the hypothyroid group were those with morphological features of advanced autophagy and Z-cells. The percentage of TUNEL (terminal... deoxynucleotidyl transferase dUTP nick end labeling) positive oogonia/ oocytes was significantly lower in the hypothyroid group. No significant difference was recorded in the expression of caspase-3, ATG7 and LC3 possibly reflecting that these proteins were not involved in the oogonia/ oocyte alteration process during prenatal rat hypothyroidism. The obtained results indicate that developmental hypothyroidism in the offspring enhances the number of Z-cells and oogonia/ oocytes altered with the advanced process of autophagy.
Keywords:ATG7 / caspase-3 / LC3 / meiosis prophase I / secondary necrosis
Source:Acta veterinaria - Beograd, 2017, 67, 1, 92-106
- Univerzitet u Beogradu - Fakultet veterinarske medicine, Beograd