THE TESTICLES 



573 



by loose intralobular connective tissue. The tubules are at first very tortuous 

 (Tubuli contorti); then they unite with other tubules, forming larger straight 

 tubules (Tubuli recti). The latter unite with adjacent tubules and converge to- 

 ward the anterior part of the attached border of the gland. In this way there are 

 formed more than a dozen larger efferent ducts (Ductuli efferentes), which pierce 

 the albuginea at a small area (about a centimeter in diameter) at the anterior part 

 of the attached border and enter the head of the epididymis. 



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

 Its head consists of a dozen or more coiled tubules, which are grouped into lobules 

 (Lobuli epididymidis). The tubules of a lobule (four or five in number) unite to 

 form a single tube, and by the union of the latter with those of the other lobules 

 there is formed a single tube, the duct of the epididymis (Ductus epididymidis). 



.y 



Fig. 514. — Right Testicle and Spermatic Cord of 

 Horse, Enclosed in Tunica \'agixaiis. 

 c, Tunica vaginalis commums; g, prominence 

 caused by tail of epididymis; p, cremaster externus 

 muscle. (After Ellenberger-Baum, Top. Anat. d. 

 Pferdes.) 



Fig. 515. — Right Testicle and Spermatic Cord of 

 Horse, Exposed. 

 a'. Lateral surface of testicle; c, tunica vagin- 

 alis, cut and reflected; d, reflection of tunica vaginalis; 

 e, mesorchium; g, tail, /i, body, i, head, of epididymis; 

 k, sinus epididymidis; /, spermatic vessels showing 

 through tunica vaginalis propria; m, end of spermatic 

 arteo'. Dotted line indicates position of ductus 

 deferens on other side of mesorchium. (After Ellen- 

 berger-Baum, Top. Anat. d. Pferdes.) 



which, by its complex coils, forms the body and tail of the epididymis and termin- 

 ates in the ductus deferens. The tubules and the coils of the duct of the epididymis 

 are held together by coimective tissue and unstriped muscle-fibers. The tubules 

 and duct are lined with ciliated epithelium, and the duct has a muscular coat which 

 consists of longitudinal and circular fibers. 



Several fcetal remnants in connection with the epididymis and adjacent part of the spermatic 

 cord have been described in man. The appendix epididymidis is a small, piriform body, 3-4 

 mm. long, which is attached to the head of the epididymis. The paradidymis consists of a number 

 of tubules which lie in the lower part of the spermatic cord close to the head of the epididymis. 

 Most of the tubules are blind and disappear in early life, but one or more may communicate with 

 the epididymis or rete testis; the latter may give rise to cysts. The ductuli aberrantes are 

 tubules that extend upward from the canal of the epididymis and end blindly. Similar structures 

 have been mentioned as occurring in the domestic animals, but authentic data in regard to them 

 are lacking. 



Vessels and Nerves. — The testicle is richly supplied with blood by the sper- 

 matic artery, a branch of the posterior aorta. The artery descends in the anterior 



