MAMMALIA 309 



Bach vas deferens leaves the scrotal sac at its proximal end, 

 together with the artery and the vein and the cremaster muscle, 

 and is directed to the dorsal side of the bladder, where it gains 

 the medial space on the dorsal side by passing between the 

 bladder and the ureter. In this space the two vasa deferentia 

 descend to open side by side on the dorsal wall of the urino- 

 genital canal or urethra. They open on an eminence called 

 the verumontanum, and on each side of this are the many 

 openings of the prostate gland; still further down are the 

 openings of Cowper's glands. Beyond this, the urethra is 

 embedded in the vascular corpus spongiosum flanked by the 

 two adpressed corpora cavernosa. The latter are attached 

 by the erector muscles to the ischia, and the former expands 

 at the anterior end to form the glans. The glans bears the 

 external opening of the urethra. It is covered with the free 

 part of the penis by a skin, the inner layer of the glandular 

 preputial pouch. 



In the female the ovaries lie on each side of the peritoneal 

 cavity. They are oval in shape, and the distended follicles 

 project from the whitish surface or are visible as clear spots. 

 Each follicle contains an ovum, and the ova are liberated at 

 periods of ovulation. They are received by the wide opening 

 of the Fallopian tube which lies close to the ovary on each 

 side. The Fallopian tube is a narrow tube which, after a slight 

 degree of convolution, expands to form the uterus. The two 

 uteri approximate and join, but do not completely fuse medially, 

 each opening by an os uteri into the median vagina. The 

 Fallopian tubes and the uteri are covered and supported by 

 a fold of the peritoneum called the broad ligament. The 

 vagina passes dorsal to and between the two ureters to open 

 below the bladder into the urinogenital canal, and this section 

 of the tube which leads to the vulva is called the vestibule. 

 The vulva is the urinogenital aperture. Its lips are called 

 the labia majora, and the anterior angle is occupied by a 

 rudimentary penis, called the clitoris. 



It is an interesting fact that the accessory organs of both 

 sexes are produced during development, that sex is manifested 

 later during development by the hypertrophy of the one and 

 the atrophy of the other. Even in the adult, remnants are 



