GENITAL ORGANS OF THE BOAR 591 



crest extends forward from the colliculus, and two mucous folds pass backward 

 from it and diverge. The mucous membrane behind the colliculus is red in color. 

 The extrapelvic part has an enlargement, the bulb, at its origin; it then gradually 

 diminishes in diameter, and is relatively very small at its termination. Other 

 features have been mentioned in preceding paragraphs. 



The bulb of the urethra has a thick tunica albuginea, enclosing a highly developed erectile 

 tissue. The cavernous spaces are wide; their walls are relatively thin and consist of fibrous tis- 

 sue and unstriped muscle. On cross-section many arteries are visible laterally. Further forward 

 the urethra is surrounded by a well-developed corpus cavernosum, which is thickest ventrally 

 here an artery of considerable size occurs on each side. ' 



In the ram the genital organs resemble in general those of the bull. But the 

 testicles are relatively much larger; a testicle of an adult ram may be four inches 

 (ca. 10 cm.) long and weigh about nine to ten ounces (ca. 250-300 gm.). They are 

 broader in proportion to their length. The prostate is entirely disseminate. The 

 bulbo-urethral glands are relatively very large. The peculiar character of the 

 terminal part of the penis is shown in the annexed figure. The urethra lies in a 

 groove on the ventral surface of the corpus cavernosum. Its terminal part pro- 

 jects commonly about an inch and a half (ca. 3-4 cm.) beyond the glans penis, 

 forming a twisted processus urethrse. 



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GENITAL ORGANS OF THE BOAR 



The scrotum is situated a short distance from the anus, and is not so sharply 

 defined from the surrounding parts as in the other animals. 



The testicles are very large and are regularly elliptical in contour. They are 

 placed so that the long axis is directed upward and backward, the free border being 

 superficial and the tail of the epididymis highest. They are comparatively soft in 

 texture. The tunica albuginea contains much elastic tissue, but no muscular fibers. 

 The mediastinum testis is an axial strand of fibro-elastic tissue, from which inter- 

 lobular septa radiate. Other septa are given off from the deep face of the tunica 

 albuginea. The interlobular tissue is abundant, and the lobulation correspond- 

 ingly distinct. The parenchyma is gray and often dark in fat animals. There is a 

 rete testis from which seven or eight efferent ducts proceed to the epididymis. 

 The epididymis is closely attached to the testicle ; its tail is very large and forms a 

 blimti conical projection at the posterior end of the testicle. 



The spermatic cord is necessarily very long (20 to 25 cm. in a boar of medium 

 size) . The ductus deferens in its testicular part is flexuous, and is closely attached 

 by the tunica vaginalis; it forms no distinct ampulla. The cremaster extemus is 

 well developed, and extends to about the middle of the scrotal part of the tunic. 



The vesiculae seminales are exceedingly large, and extend into the abdominal 

 cavity. They are three-sided pyramidal masses, are in apposition with each other 

 medially, and cover the posterior part of the bladder and the ureters, the ductus 

 deferentes, the body of the prostate, and the anterior part of the urethra and bulbo- 

 urethral glands. They are pale pink in color, distinctly lobate and glandular in 

 structure, and are enclosed in a thin fibrous capsule. Half a dozen or more large, 

 thin-walled ducts emerge from the medial surface of each and converge to a much 

 smaller excretory duct. The latter passes back lateral to the ductus deferens, and 

 terminates at a slit-like opening on the colliculus seminalis. The two ducts may 

 unite. 



In the adult boar the vesiculae are about five to six inches (ca. 12 to 15 cm.) long, two to 

 three inches (ca. 5 to 8 cm.) wide, and one and a half to two inches (ca. 4 to 5 cm.) thick; they 

 weigh about 6 to 8 ounces each. They have a branched tubular structure and are distinctly di- 



