Tamoxifen Affects Early Oocyte Differentiation in Mice


Roshangar L *, Soleimani Rad J , Afsordeh K ,

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Objective: In human early oocyte differentiation occurs during fetal life. But in mice it takes place in early postnatal period providing a valuable model for investigating the effect of different factors on oocyte differentiation. It is thought that estrogen may have a role on early oocyte development and therefore the aim of the present study is to evaluate the effect of tamoxifen on early oocyte differentiation and follicular development in mice. Materials and Methods: In this study 30 adult female and 15 adult male mice are used. Two female mice at their sterous cycle were housed in a cage for mating. Observation of vaginal plaque was considered as the first day of pregnancy and the mice on the 13th day of pregnancy received 100 micro gram tamoxifen as ip injection. After delivery the 2 3 6 and 7 days old pups were sacrificed and their ovaries removed and fixed and prepared for light and electron microscopy. Ultrastructural morphology of differentiating oocytes were studied and the number of oocyte nests and diameter of primordial and primary follicles were determined. Results: Microscopy showed that oocyte nests were formed on 2-3 day old pups and follicles were distinguished on 6 and 7 days. Morphometric studies revealed that the number and diameter of oocyte nests were significantly reduced in experimental group in comparison to control group ( p