Anatomical and histological study of the penis of the Sunda porcupine (Hystrix javanica)

Assisted reproductive technologies (ARTs) are one reproductive strategy to support conservation efforts for species with decreasing populations. To develop these techniques, the variation of reproductive traits among animals must be considered for successful implementation. In artificial insemination (AI) or in vitro fertilization (IVF), semen collection using penile vibratory stimulation requires basic anatomical data of the penis. In the Sunda porcupine (Hystrix javanica), however, there is no such information. Therefore, in this study, anatomical and histological examinations of the penis of the Sunda porcupine were performed to provide baseline data that can be used for further studies to develop ARTs for this species. Six penes from euthanized wild adult male Sunda porcupines obtained in Central Java, Indonesia, were utilized in this study. Characteristically, the penis of the Sunda porcupine had a sacculus urethralis and glans penis with penile spines, which demonstrated regional structural differences, and the os penis was capped by a cartilaginous structure. The distribution pattern of the penile spines may be useful for mechanical reproductive procedures such as efficient vaginal and penile stimulation. Immunohistochemically, androgen receptors (AR) were localized in the epithelial cells of the surface of the glans penis and sacculus urethralis, and may play a role in the maintenance of the keratinized penile spines.