506 MALE GENITAL ORGANS OF THE DOG 



The prepuce has a narrow orifice, around which there are a number of stiff hairs. 

 The cavity is partially divided by a circular fold into a posterior narrow portion 

 and a much wider anterior portion. The lining membrane of the posterior part is 

 papillated, and is in close contact with the penis. In the dorsal wall of the wide part 

 there is a circular opening which leads into a cul-de-sac, the preputial diverticulum. 

 This pouch is ovoid in form (when distended), and varies greatly in size in different 

 subjects. It extends for the most part backward over the narrow part of the 

 prepuce. Its cavity is partially divided by a narrow median septum. It contains 

 usually decomposing urine and macerated epithelium, which have a characteristic 

 and very unpleasant odor. Concrements have been found in it. • 



Oehmke found that a cast of the pouch in a Yorkshire boar weighing about 500 pounds 

 measured 9 cm. in length, 123/2 cm. in breadth, and G cm. in height. The opening into the pre- 

 puce will admit two fingers in the adult, l)ut is ordinarily closed by folds of the lining membrane. 

 The sac is much smaller in animals which were castrated young, and the opening is vertical and 

 further back; in them it is often empty or contains only a little clear urine. The pouch is covered 

 by a layer of striped muscle which is mainly derived from the homologue of the protractor of the 

 prepuce of ruminants. 



The urethra has a very long pelvic portion (ca. 15 to 18 cm. long in the adult) ; 

 it is inclosed (with the pars disseminata of the prostate) ])y a thick urethral muscle. 

 There is a distinct bulb at the root of the penis. The penile part is of small caliber, 

 and is surrounded by erectile tissue which, however, does not extend to the 

 extremity of the penis. 



MALE GENITAL ORGANS OF THE DOG 



The scrotum is situated about half wa}^ l^etween the inguinal region and the 

 anus. The skin covering it is pigmented and is covered sparsely with fine hairs. 

 The raphe is not very distinct. 



The testicles are relatively small, and have a round-oval form. The long 

 axis is oblique, and is directed upward and backward. The mediastinum testis 

 is central and is well developed. The epididymis is large, and is closely attached 

 along the outer part of the dorsal l)order of the testicle. 



The spermatic cord and the tunica vaginalis are long; they cross the side of 

 the penis very obliquely. The upper end of the tunic is sometimes closed, so that 

 there is then no vaginal ring. The vasa deferentia have very narrow ampullae. 



The vesiculae seminales are absent; hence there are no ejaculatory ducts. 



The prostate is relatively large; it is yellowish in color, dense in structure, 

 and lies at the anterior border of the pubis. It is globular, and surrounds the 

 neck of the bladder and the urethra at their junction. A faint median furrow 

 indicates a division into two lateral lobes. The capsule and stroma contain a large 

 amoimt of unstriped muscle. The ducts are numerous. Lobules of prostatic 

 tissue (pars disseminata) are also found on the urethra further back. The gland 

 is subject to much variation in size, and is often enlarged, especially in old subjects. 



The uterus masculinus is a very small saccule (Utriculus prostaticus), often 

 difficult to find. 



The bulbo-urethral (Cowper's) glands are absent. 



The penis presents several special features. In its posterior part there are two 

 distinct corpora cavernosa, separated by a median septum penis. In its anterior 

 part there is a bone, the os penis, which in large dogs reaches a length of four 

 inches (ca. 10 cm.) or more. It is regarded as a continuation forward of the corpus 

 cavernosum. Ventrally it is grooved for the urethra; dorsally it is convex, and 

 anteriorly it becomes smaller and has a curved fibrous prolongation. The glans 

 penis is very long, extending over the entire length of the os penis; posteriorly it 



