title: Altered state of primordial follicles in neonatal and early infantile rats due to maternal hypothyroidism: Light and electron microscopy approach.
abstract: Thyroid hormones (TH) are one of the key factors for normal prenatal development in mammals. Previously, we showed that subclinical maternal hypothyroidism leads to premature atresia of ovarian follicles in female rat offspring in the pre-pubertal and pubertal periods. The influence of decreased concentration of TH on primordial follicles pool formation during neonatal and early infantile period of rat pups was not investigated previously. Maternal hypothyroidism during pregnancy has irreversible negative influence on primordial follicles pool formation and population of resting oocytes in female rat offspring. The study was done on neonatal and early infantile control (n-10) and hypothyroid (n-10) female rat pups derived from control (n-6) and propylthiouracil (PTU) treated pregnant dams (n-6), respectively. Ovaries of all pups were removed and processed for light and transmission electron microscopy (TEM). Number of nests, oogonia and oocytes per nest, primordial, primary, secondary and preantral follicles were determined. Screening for overall calcium presence in ovarian tissue was done using Alizarin red staining. Morphology and volume density of nucleus, mitochondria and smooth endoplasmic reticulum (sER) in the oocytes in primordial follicles was also assessed. Caspase-3 and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL), both markers for apoptosis, and proliferating cell nuclear antigen (PCNA) for proliferation were determined in oocytes and granulosa cells in different type of follicles. In neonatal period, ovaries of hypothyroid pups had a decreased number of oogonia, oocytes and nests, an increased number of primordial follicles and a decreased number of primary and secondary follicles, while in early infantile period, increased number of primary, secondary and preantral follicles were found. Alizarin red staining was intense in hypothyroid neonatal rats that also had the highest content of dilated sER. Number of mitochondria with altered morphology in both groups of hypothyroid pups was increased. Apoptosis markers have not shown significant difference between groups but PCNA had an increased expression in the oocytes and granulosa cells in primordial follicles of hypothyroid rats. Light and electron microscopy analysis indicate that previously detected premature ovarian follicular atresia in pre-pubertal and pubertal hypothyroid rats is preceded with premature formation of primordial follicles followed by slight changes on sER and mitochondria in examined oocytes, and increased expression of PCNA.
authors: State University of Novi Pazar, Department of Biomedical Sciences, Vuka Karadžića bb, 36300 Novi Pazar, Serbia. Electronic address: reginadelphy@yahoo.com.
authors: Jelena
authors: J
authors: Danilović Luković
authors: University of Belgrade, Center for Electron Microscopy, Faculty of Biology, Studentski trg 16, 11000 Belgrade, Serbia.
authors: Aleksandra
authors: A
authors: Korać
authors: University of Belgrade, Department of Histology and Embryology, Faculty of Veterinary Medicine, Bulevar oslobođenja 18, 11000 Belgrade, Serbia.
authors: Ivan
authors: I
authors: Milošević
authors: University of Belgrade, Department of Histology and Embryology, Faculty of Veterinary Medicine, Bulevar oslobođenja 18, 11000 Belgrade, Serbia.
authors: Tijana
authors: T
authors: Lužajić
authors: University of Belgrade, Institute of Histology and Embryology, School of Medicine, Višegradska 26, 11000 Belgrade, Serbia.
authors: Nela
authors: N
authors: Puškaš
authors: University of Belgrade, Department of Pathophysiology, Faculty of Veterinary medicine, Bulevar oslobođenja 18, 11000 Belgrade, Serbia.
authors: Milica
authors: M
authors: Kovačević Filipović
authors: University of Belgrade, Department of Histology and Embryology, Faculty of Veterinary Medicine, Bulevar oslobođenja 18, 11000 Belgrade, Serbia.
authors: Anita
authors: A
authors: Radovanović
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D053148:Caspase 3 / Q000235:genetics; D003409:Congenital Hypothyroidism / Q000473:pathology*; D018871:Endoplasmic Reticulum, Smooth / Q000648:ultrastructure; D005260:Female; D007037:Hypothyroidism; D020287:In Situ Nick-End Labeling; D008853:Microscopy; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000473:pathology; D009865:Oocytes / Q000737:chemistry / Q000473:pathology / Q000648:ultrastructure*; D006080:Ovarian Follicle / Q000503:physiopathology / Q000648:ultrastructure*; D010053:Ovary / Q000166:cytology / Q000503:physiopathology / Q000648:ultrastructure; D011247:Pregnancy; D011248:Pregnancy Complications; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics; D011441:Propylthiouracil; D051381:Rats
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D011441:Propylthiouracil; D053148:Caspase 3
keywords: Caspase-3; Hypothyroidism; Oocyte ultrastructure; PCNA; Primordial follicle; TUNEL