Development of the penis and clitoris in the tammar wallaby, Macropus eugenii

Abstract

The development of the phallus from the indifferent stage to sexual dimorphism has not been described in any marsupial. This study describes the morphological and histological changes occurring in the development of the phallus of the tammar wallaby. The development of the penis and clitoris in the tammar closely follow the most widely accepted model for the development of the same organs in eutherian mammals. The urogenital plate that is present in both sexes at birth hollows out to form a urogenital groove at approximately 70 days postpartum (p.p.). There is then greater growth of the phallus in males than in females, which results in sexual dimorphism in length approximately 100 days p.p...