The functions of the individual organs of reproductive systems are fairly uniform throughout the primates, but, in spite of this physiological homology, there is a remarkable degree of variation in minor detail of organs between groups—particularly in the external genitalia, which, by their variation, provide a morphological basis for the reproductive isolation of the species. There could be no more effective barrier to mating between different species than incompatibility of the male and female sex organs. The testes, with a few exceptions among the lemurs, in which they are withdrawn seasonally, lie permanently in the scrotal sac, to which they migrate from their intra-abdominal position some time before birth in humans or after birth in nonhuman primates. In all primates except modern humans, tarsiers, and some South American monkeys, the penis contains a small bone called the baculum , a typically mammalian character. The uterus of female primates shows all grades of transition between the two-horned bicornuate uterus, typical of most mammals, to the single-chambered simplex uterus of the higher primates and humans. Variations between primate taxa are demonstrated most strikingly by the glans penis, scrotum, and perineum of the male and by the clitoris and labial folds of the female vulva. In the clitoris, there is in most primates a small bone, the baubellum, homologous with the baculum of the penis. The length and form of the clitoris, which when elongated mimics the penis as in spider monkeys , for instance , are a potent source of confusion in determining the sex of certain New World primates. The coloration of the male scrotum in forest-living primates, particularly of the guenon genus Cercopithecus and in drills and mandrills genus Mandrillus , shows an infinite range of variations and provides a species-recognition signal of considerable effectiveness.
Male and female genitalia
View research View latest news Sign up for updates. Macroscopic and histological changes were examined on the female reproductive organs of Japanese monkeys Macaca fuscata with varying reproductive status in enclosed and provisioned troops. The weight and size of reproductive organs are described. The size of uterus declined in 2—3 months after parturition.
Alouatta guariba clamitans brown howler monkey is an endemic primate from the southeastern Brazil tropical forests, classified as near threatened by the IUCN Red List The genus Alouatta is one of the most difficult New World monkeys to breed and rear in captivity. In this study we examined the macroscopic and histological aspects of the female genital tract of wild brown howler monkeys to provide baseline information for future reproduction research. The anatomical relationship between the vagina, uterus, broad ligament, oviducts and ovaries are those of a typical primate reproductive tract. The fundic portion of the uterus is globoid, the cervix is well developed, which confers to the uterus an elongated shape, and the vagina is a long flattened channel. Histological analysis conducted in females in the follicular phase revealed large quantities of interstitial luteinized tissue in the ovaries, a stratified nonkeratinized vaginal epithelium, lack of glands in the vaginal mucosa and simple tubular endometrial glands.
Sexual swellings are enlarged areas of genital and perineal skin occurring in some female primates that vary in size over the course of the menstrual cycle. Though heavily investigated, the ultimate function of sexual swellings remains unknown. Alone, however, no single hypothesis is believed to account for the function of sexual swellings; a combination of these theories may be more appropriate. Sexual swellings are water-filled edemas of mainly the external or internal genitalia of female primates.