REPRODUCTIVE ORGANS IN ANIMALS 25 



The above description applies more particularly to the human 

 penis, but in other mammals it has the same essential structure. 

 In certain orders (Carnivora and Rodentia) it is provided with 

 a cartilaginous or bony support, the os penis. Some species 

 are provided with what are apparently sexual irritants, such as 

 the structures which project from the penis in the rhinoceros 

 and the tiger, and the pair of horny styles attached to that organ 

 in the guinea-pig. In the ram and certain other Ungulata there 

 is a peculiar filiform appendage attached to the left side of the 

 penis which has undergone torsion, and the urethra opens to the 

 exterior at the end of this appendage. This structure contains 



Fig. 1.3. — Distal end of ram's penis, as seen from the left side, showing 

 glans and filiform appendage. The prepuce is folded back. Slightly 

 reduced. 



a pair of fibro-cartilage supporting bodies as well as erectile 

 tissue, and its function appears to be insertion into the mouth 

 of the uterus during copulation, since if this filiform appendage 

 is cut off the ram is generally rendered barren. 



The penis is in front of the scrotum, and behind the scrotum 

 is the anus. The tissue between the scrotum and the anus forms 

 the perineum, and the corresponding space in the female is 

 similarly designated. 



The Female Organs 



The ovaries are a pair of organs lying in the cavity of the 

 abdomen with the dorsal wall of which they are connected by 

 the broad ligament. This stretches across the body wall in the 

 region in question, and to it the oviducts and uterus are also 

 attached. Each ovary, as shown in microscopic sections, is 

 formed of stroma or ground substance of connective tissue 

 containing blood vessels and a number of vesicles of varying 

 sizes known as the Graafian follicles. The smallest of these — 

 the primordial follicles — however, have no cavity, but consist 

 of ova surrounded by a row of epithelial cells ; these lie just 



