486 



THE MALE GENITAL ORGANS OF THE HORSE 



is the visceral layer of the serous envelop of the cord and testicle; this is reflected 

 from the attached border of the gland, leaving an uncovered area at which the vessels 

 and nerves in the spermatic cord reach the testicle. Beneath this serous covering is 

 the tunica albuginea, a strong capsule composed of dense white inelastic fibrous tissue 

 and unstriped muscle-fibers. From the deep surface of this tunic delicate mem- 

 branous septa (Septula testis) pass into the gland, dividing it into pyramidal 

 spaces, the bases of which are peripheral. At the anterior part of the attached 

 border of the testicle connective tissue and smooth muscle-fibers pass into the 

 substance of the gland, forming the mediastinum testis ; from this the septa 

 radiate. The mediastinum contains a network of fine canals, the rete testis; 



Fig. 390. — Inguinal Region of Stallion, with Testicles Exposed. 

 a, a' , Testicles; 6, scrotum, opened and reflected; c, tunica vaginalis communis, opened and reflected; 

 d, ligament of epididymis; e, tunica vaginalis propria (mesorchium) ; /, vas deferens; g.g', tail of epididymis: h, body 

 of same; i, head of same; k, digital fossa or sinus epididymidis; /, spermatic vessels showing through tunica 

 vaginalis propria; m, spermatic artery; n, prepuce; n', raphe; o, preputial orifice. (After EUenberger-Baum, 

 Top. Anat. d. Pferdes.) 



it is traversed by blood-vessels, which radiate on the septa to the deep face of the 

 tunica all)uginea, forming a delicate network — the so-called tunica vasculosa. 

 The spaces imperfectly marked off by the septa contain the parenchyma testis, 

 which consists of seminiferous tubules (Tul)uli seminiferi), supported by loose 

 intortubular connective tissue. The tubules are collected into small masses or 

 lobules (Lol)uli testis). They are at first very tortuous (Tubuli contorti); to- 

 ward tlic apex of the lobule they unite with other tubules, forming larger straight 

 tubules (Tul)uli recti); these pass into the mediastinum testis, where they form 

 the rete testis. From the latter a number (ca. 15 to 20) of larger efferent tubules 

 (Vasa efferentia) pierce the albuginea and enter the head of the epididymis. 



The epididymis is covered by the tunica vaginalis propria and a thin albuginea. 



