1420 



THE URINOGENITAL ORGAXS 



rounded nodular elevations known as the carunculae myrtiformes (carunculae 

 hi/menales) are found as the remains of the structure. 



The clitoris (Figs. 1174, 1175) is an erectile structure which is the morpho- 

 logic homologue oAhe penis; unlike the penis, however, it is not traversed by the 

 urethra. It is situated beneath the anterior commissure (or mons Veneris) and 

 is partly hidden between the anterior extremities of the labia minora. It is com- 

 posed of a body and two crura; the extremity of the body is surmounted by a small 

 glans. 



e artery to the 

 nerve supply is by 



((glandulavestibularis major [Bartholiui]) (Fig. 1 177). 

 posterior part of the commencement of the vagina is a round 

 Ol'ong body, of a reddish-yellow color, and of the size of a horse-bean, analo- 

 0us to Cowper's gland in the male. It is called the gland of Bartholin, the gland 

 of Duverney, the vulvovaginal gland, or the suburethral gland. Bartholin's gland 

 lies partly in the inferior or anterior leaf of the triangular ligament. The pos- 

 terior portion of the bulbus vestibuli and the Bulbocavernous muscle partly cover 

 it. Each gland opens by means of a long single duct immediately external to 

 the hymen, in the angle or groove between it and the nympha (Fig. 1176). 



DEVELOPMENT OF THE URINARY AND GENERATIVE ORGANS. 



The permanent organs of the adult are preceded by a set of purely embryonic structures which, 

 with the exception of their ducts, almost entirely disappear before birth. These embryonic 

 structures, all developed from the intermediate cell mass of mesodermal tissue, are on either 

 side; the pronephros, the mesonephros, the Wolffian (mesonephric) duct, and the Miillerian 

 duct (oviduct). The pronephros disappears very early; the structural elements of the meso- 

 nephros mostly atrophy, but in their place is developed the genital gland, in association with 

 which the mesonephric duct remains as the duct of the male genital gland, the oviduct as that of 

 the female. 



The pronephros is an early embryonic structure in all vertebrates. It develops at about the 

 level of the heart by a proliferation of the mesodermal cells of the intermediate cell mass. In it 

 appear (a) a longitudinal cord of cells, which later acquires a lumen to form the pronephric 

 duct; (b) two transverse pronephric tubules develop as invaginations of the coelomic meso- 

 thelium. Of these, the cephalic one acquires a lumen and opens into the coelomic cavity; the 

 other remains a solid cord of cells. Neither tubule becomes connected with the pronephric duct. 

 The pronephric duct remains to become the Wolffian duct of the next stage, while the tubules 

 are represented, in the adult, by t'le hydatids at the fimbriated end of the Fallopian tube in the 

 female, and by the stalked hydatid at the upper end of the testis in the male. 



The Mesonephros, Miillerian Duct, and Genital Gland. On the inner side of the Wolffian 

 duct a series of tubules, the Wolffian tubules, are developed. Each tubule opens laterally into 

 the duct, while its opposite end is invaginated by a tuft of capillary bloodvessels to form a glom- 



