THE MALE GENITAL ORGANS 



The male genital organs (Organa genitalia masculina) are: (1) The two 

 testicles, the essential reproductive glands, with their coverings and appendages; 

 (2) the vasa deferentia, the ducts of the testicles; (3) the vesiculae seminales; 

 (4) the prostate, a musculo-glandular organ; (5) the two bulbo-urethral (or Cow- 

 per's) glands; (6) the male urethra, a canal which transmits the generative and 

 urinary secretions; (7) the penis, the male copulatory organ. The vesiculae 

 seminales, the prostate, and the bulbo-urethral glands discharge their secretions 

 into the urethra, where they mix with the seminal fluid secreted by the testicles; 

 hence they are often termed the accessory sexual glands. 



MALE GENITAL ORGANS OF THE HORSE 



THE TESTICLES 



The testicles (Testes) are situated in the inguinal region, inclosed in a diverti- 

 culum of the abdomen termed the scrotum. Their long axes are nearl}' longitu- 

 dinal. They are ovoid in form, but consideral)ly compressed from side to side. 

 Each presents two surfaces, two borders, and two extremities. The internal and 

 external surfaces (Facies medialis, lateralis) are convex and smooth. The free 

 or ventral border (Margo liber) is convex in both directions. The attached or 

 dorsal border (Margo epididymidis) is nearly straight, and is the one by which the 

 gland is suspended in the scrotum l)y the spermatic cord; the epididymis is at- 

 tached to this border and overlies it externally. The anterior and posterior 

 extremities (Extremitas capitata, cauclalis) are rounded. 



At the anterior extri^inity tliere is often a sessile or pedunculated sac which contains a clear 

 fluid; this is the appendix testis or hydatid of IMorgagni, from which a thread-like process 

 extends backward toward the vas deferens. It is regarded as a remnant of the Miillerian duct 

 of the embryo. 



A testicle of average size of an adult stallion is about four or five inches (ca. 

 10 to 12 cm.) long, two and a half inches (ca. 6 to 7 cm.) high, and one and a half to 

 two inches (ca. 4 to 5 cm.) wide; it weighs about ten and one half ounces (ca. 300 

 grams). They vary much in size in different subjects, and are commonly of un- 

 equal size, the left one being more often the larger 



The epididymis is adherent to the attached border of the testicle, and overlaps 

 somewhat the external surface. Its anterior enlarged end is termed the head 

 or globus major (Caput epididymidis), and its posterior, slightly enlarged end is 

 the tail or globus minor (Cauda epididymidis) ; while the intermediate narrow part 

 is the body (Corpus epicUdymidis). The head is closely connected with the testicle 

 by the efferent ducts of the latter, by connective tissue, and by the serous membrane. 

 The body is less closely attached by the serous covering, which forms externally a 

 pocket beneath the epididymis termed the digital fossa (Sinus epididymidis). 

 The tail is firmly attached to the posterior extremity of the testicle by a short 

 ligament (Lig. epididymidis) , formed by a thick fold of the tunica vaginalis, which 

 contains smooth muscle-fibers; it is continued by the vas deferens. 



Structure of the Testicle and Epididymis. — The greater part of the surface 

 of the testicle is covered by a serous membrane, the tunica vaginalis propria, which 



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