Intrauterine Development of Female Genital Organs in Cavia porcellus (Rodentia: Caviidae)

To contribute to the knowledge of the embryology of an important experimental model for studies related to the reproduction, a study was conducted to describe the morphological events of sexual differentiation of female genital organs during the intrauterine life of Cavia porcellus from 20th to 68th gestational day. Eighteen embryos and fetuses at days 20, 25, 30, 45, and 60 of pregnancy and near term (n = 3 animals for each gestational period) were utilized. Embryos and fetuses were dissected, and the genital organs processed for light microscopy. Sexual differentiation on females of Cavia porcellus was observed only after the 25th day of gestation with the development of the ovary. However external genitalia acquired female characteristics only at 45 days of gestation. At the end of gestation, the external genitalia had labia, vaginal external ostium occluded by the vaginal closure membrane and penile clitoris with the external urethral ostium opening at the top of the organ. Microscopically, the tubular genital organs (uterine tubes and horns, uterus and vagina) were lined with internal epithelium and loose connective tissue at 39 days of pregiancy. At the end of the pregnancy tissue layers characteristics of tubular genital organs are slightly differentiated.