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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 ductus deferentes, the ducts of the testicles; (3) the vesicula 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 vesicule 
seminales, the prostate, and the bulbo-urethral glands discharge their secretions 
into the urethra, where they mix with the fluid secreted by the testicles; hence they 
are often termed the accessorv sexual glands. 
GENITAL ORGANS OF THe STALLION 
THE TESTICLES 
The testicles (Testes) are situated in the inguinal region, enclosed in a divertic- 
ulum of the abdomen termed the scrotum. Their long axes are nearly longitu- 
dinal.t They are ovoid in form, but considerably compressed from side to side. 
Each presents two surfaces, two borders, and two extremities. The medial and 
lateral surfaces (Facies medialis, lateralis) are convex and smooth; the former is 
somewhat flattened by contact with the septum scroti. The free border (Margo 
liber) is ventral and is convex. The attached or epididymal border (Margo epi- 
didymidis) is dorsal; it is nearly straight, and is the one by which the gland is 
suspended in the scrotum by the spermatic cord; the epididymis is attached to this 
border and overlies it laterally. ‘The anterior and posterior extremities (Extremitas 
capitata, caudalis) are rounded. 
At the anterior extremity there is often a sessile or pedunculated sac which contains a clear 
fluid; this is the appendix testis, from which a thread-like process extends backward toward 
the ductus 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 em.) long, two and a half to three inches (ca. 6 to 7 em.) high, and two 
inches (ca. 5 em.) wide; it weighs about eight to ten ounces (ca. 225-300 grams). 
They vary much in size in different subjects, and are commonly of unequal size, 
the left one being more often the larger. 
The epididymis is adherent to the attached border of the testicle, and overlaps 
somewhat the lateral surface. Its anterior enlarged end is termed the head (Caput 
_ epididymidis) ; and its posterior, slightly enlarged end is the tail (Cauda epididy- 
midis); the intermediate narrow part is the body (Corpus epididymidis). 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 laterally a pocket beneath the epididymis 
termed the sinus epididymidis. The tail is continued by the ductus deferens; it is 
| attached to the posterior extremity of the testicle by a short ligament (Lig. epididy- 
_ midis), which is formed by a thick fold of the tunica vaginalis and contains smooth 
muscle-fibers. 
_ 1 When the testicle is drawn up or has not completed its descent into the scrotum, its long 
| axis is almost vertical. 
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