250 



THE MALE REPRODUCTIVE SYSTEM 



albuginea, with outer fibers mainly longitudinal and inner fibers 

 circular. Between the two corpora this sheath forms a more or 

 less complete septum, but toward the glans both corpora may 

 communicate. 



The corpus cavernosum urethra is siu'roimded by a less dense 

 tunica albuginea, in which circular smooth muscle may appear 

 toward the urethral wall. The venous sinuses are more imiform 

 and more elastic fibers are present. When the os priapi, or penis 



Fig. 154. — Photograph of a cross-section of the penis of a chipmunk near the tip. 

 It is externally surrounded by the skin, within which is connective tissue. The corpus 

 cavernosum penis is a large bean-shaped mass. The V-shaped opening is the urethra, 

 below which is the vas deferens; both of these ducts are surrounded by scanty corpus 

 cavernosum urethra tissue. 



bone, is present, it forms just ab()\e the urethra from mesenchyme 

 of the developing ])enis. 



Surrounding the C()r])ora and forming the general groundwork 

 of the penis is a vascular fibroelastic connective tissue which is 

 covered externally by the skin in whose subcutaneous tissue some 

 skeletal muscle may be found. The outer knob-like end of the 

 penis, the glans, is composed of a mass of dense vascular connective 

 tissue covered by a reflected fold of skin, the pre])uce. 



At times of sexual excitement, erection of the penis follows 

 reflexes conducted to the muscular wall of the arteries leading into 



