1256 



UROGENITAL SYSTEM 



each being of a flattened oval form, with two surfaces, medial and lateral, two 

 borders, anterior and posterior, and two extremities, superior and inferior. To the 

 whole of the posterior border there is attached the epididymis, formed by the 

 efferent ducts. The testis is obliquely placed, so that the medial surface also looks 

 somewhat forward and downward. 



The surface of the testis is covered b}^ the visceral layer of the tunica vaginalis 

 propria except where it is in contact with the epididymis, and is formed by a 

 dense white inelastic capsule, the tunica albuginea, beneath which is a looser and 

 more vascular layer known as the tunica vasculosa. From the inner surface of the 

 albuginea, lamellae of connective tissue, known as septula, converge toward the 

 posterior border of the testis and toward its upper part unite together to form a 

 network (fig. 1018), the mediastinum testis (or corpus Highmori), through which 

 blood-vessels and lymphatics enter and leave the testis, while by the interspaces 

 of the network, known as the rete testis, the tubules of the testis are placed in com- 

 munication with the epididymis. 



The septula divide the substance of the testis into a number of compartments or lobules, 

 each of which is occupied by a number of slender, greatly contorted canals, the seminiferous 

 tubules [tubuli seminiferi], from whose epithelial lining the spermatozoa are formed. The 

 tubules of each lobule converge to form a single, almost straight duct and these tubuli recti pass 



Fig. 1018. — Diagram of the Testicular Tubules. 



Ductus epididymidis 

 Lobulus epididymidis 



Efiferent ducts 



Lobuli 



Tunic albuginea receiving attach- 

 ment of septula 



Tubulus rectus 



Rete testis in mediastinum testis 



- Ductus epididymidis 



I%- Ductulus aberrans 

 1%- Ductus deferens 



toward the mediastinum, where they open into the rete testis. In the lobules the seminif- 

 erous tubules are imbedded in a loose connective tissue that contains certain peculiar cells, 

 the interstitial cells, to which has been attributed the formation of an internal secretion. 



The epididymis (fig. 1017), which lies along the posterior border of the testis, 

 is an elongated structure with a body [corpus epididymidis], enlarged above to form 

 the head [caput] and to a less extent below to form the tail [cauda]. It is invested 

 by a tunica albuginea, continuous with, but much thinner than that of the testis, 

 and is formed mainly by the greatly contorted duct of the epididymis, which 

 represents the beginning of the ductus deferens. 



The head is formed by 12-14 tubules, the efferent ducts (fig. 1018), which take their origin 

 from the rete testis as almost straight tubules, but gradually become greatly coiled, so that 

 each duct has the form of an elongated cone, its coiled portion forming what is termed a lobulus 

 epididymidis. At their coiled ends the various efferent ducts open into a single tube, the 

 ductus epididymidis. Its diameter is only about 0.4 mm., but it measures 6.0-7.0 metres (18-21 

 feet) in its entire length, being coiled so extensively as to be contained within the body and 

 tail of the epididymis. In this latter region it passes over into the ductus deferens. 



Vessels. — The principal artery supplying the testis is the internal spermatic, from which 

 branches are also sent to the epididymis. The deferential artery, a branch of the superior 

 vesical, also sends branches to the c])ididyinis and enters into extensive anastomoses with the 

 testicular branches of the internal spermatic, and anastomoses also occur with the vessels 

 supplying the scrotum. The veins correspond witli tiie arteries. The lymphatics of the testis 

 and epididymis unite to form four to six large stems which pass upward in the spermatic cord 

 to terminate in the lowcsr lumbar nodes. 



Morphology. — The testis is primarily an abdominal organ and is developed in close relation- 

 ship with the provisional kidney [mesonophros] who.se duct, indeed, becomes the ductus deferens 



