OBJECTIVETo establish the rat model of estradiol valerate medication in early pregnancy, and to investigate the effects of estradiol valerate on the development of the reproductive system of the first filial generation (F1) male rats by evaluating the anogenital distance (AGD) and the development of the testis and epididymis.

METHODSPregnant SD rats were divided at random into a blank control group and a low dose, a medium dose and a high dose medication group to receive intragastric estradiol valerate at 0.2 mg/kg, 0.5 mg/kg and 0.8 mg/kg, respectively. The newborn F1 male rats were normally fed. Their anogenital distances were measured on postnatal day (PND) 3 and 21, the organ coefficients of the testis and epididymis (testicular and epididymal weight g/body weight 100 g) were obtained on PND 60, the morphological changes of spermatogenic cells were observed by testis biopsy, and the diameter of the seminiferous tubule and epithelial height were measured.

RESULTSThere was no significant difference between the control and medicated F1 male rats in AGD on PND 3 and 21 (P > 0.05), nor in the organ coefficients of the testis and epididymis on PND 60 (P > 0.05), nor in the diameter of the seminiferous tubule and epithelial height.

CONCLUSIONMedication of estradiol valerate (0.2 -0.8 mg/kg) to rats in early pregnancy neither significantly affects the reproductive system development, nor induces obvious histological changes of the testis in the sexual maturation period of their F1 males.