OVOTESTIS VARIABILITY IN YOUNG AND ADULT FEMALES OF THE MOLE TALPA-OCCIDENTALIS (INSECTIVORA, MAMMALIA)

The age-related evolution and ontogenic origin of the ovotestes in fer tile females of the Spanish mole (Talpa occidentalis) were studied. Vo lume of the ovotestis and its ovarian and testicular components, size of the epididymis and testicular cords, number of ovarian follicles an d testicular cords, uterus weight, and age index were analyzed statist ically in a large sample of young and adult individuals of this specie s. Comparison of means and linear correlation analyses were done. Most variables were shown to be age dependent, with a period of rapid chan ge during puberty. In adult animals, volume of the ovarian portion and uterus weight followed a seasonal cycle of sexual activity. Interindi vidual variability was evident in most of the variables investigated e xcept for the number of testicular cords per ovotestis, which remained unchanged throughout the animal's life and hence was not inversely co rrelated with the number of ovarian follicles. This finding ruled out an ovary-testis transdifferentiation hypothesis for the ontogenic orig in of the testicular tissue in the ovotestes of female moles. An alter native hypothesis based in the absence of oocytes in a portion of the undifferentiated fetal gonad is proposed in accordance with a new gene ral model for mammalian sex determination. (C) 1996 Wiley-Liss, Inc.