284 



HISTOLOGY. 



FIG. 323. CROSS SECTION 

 OF AN ARTERY OF THE 

 BULBUS URETHRAE, 

 SHOWING THICKEN- 

 INGS OF THE INTIMA 

 AT x. Elastic tissue 

 stain. (After Eberth.) 



mer pass the length of the cavernous body and end in the glans. These 

 arteries have particularly thick walls of circular muscle and in cross sections 

 the intima may be seen to form coarse rounded projections into the lumen. 

 These contain longitudinal muscles and circular subdivisions of the inner 

 elastic membrane (Fig. 323). The arteries in the 

 corpus cavernosum produce capillaries found chiefly 

 toward the albuginea. The capillaries empty into 

 thin walled venous spaces which appear as endothe- 

 lium-lined clefts, in a connective tissue containing 

 many smooth muscle fibers. The cavernous body 

 is permeated with these veins which, at times of 

 sexual excitement, become distended with blood, re- 

 ducing the tissue between them to thin trabeculae. 

 Some arteries connect directly with the venous spaces, 

 and such as appear coiled or C shaped in a collapsed 

 condition are called arteriae helicinae. The venae 

 cavernosae have such very thick walls that they 

 resemble arteries. They contain an abundance of inner longitudinal 

 muscle fibers and since these are not evenly distributed but occur in col- 

 umns, the lumen of the veins is usually crescentic or stellate in cross sec- 

 tion. Emissary veins pass out through the albuginea and empty into the 

 median dorsal vein of the penis. 



The corpora cavernosa penis are a 

 pair of structures similar to the 

 cavernous body of the urethra, and are 

 found side by side above it (Fig. 324). 

 The septum between them is perforated 

 distally so that they communicate with 

 one another. Each is surrounded by 

 a very dense albuginea, i mm. thick, 

 divisible into an outer longitudinal 

 and an inner circular layer of fibrous 

 tissue. The septum is formed by 

 the union of these tunicae. The 

 cavernous or erectile tissue of which 

 the corpora are composed, is essen- 

 tially like that around the urethra. 



All three cavernous bodies are surrounded by subcutaneous tissue 

 and fascia, containing blood vessels, lymphatics and nerves, especially along 

 the upper surface of the penis. The lymphatic vessels form a superficial 

 and a deep set, the latter receiving branches from the urethra. The 



FIG. 324. CRO 



:TION OF A PENIS. 



Skin; b., subcutaneous tissue; c., sub- 

 fascial tissue; d., dorsal vein; e., corpora 

 cavernosa penis; f., urethra; g., corpus 

 cavernosum urethrae. (Bailey.) 



