684 



A MANUAL OJ^ ANATOMY 



towards the mediastinum. Each tubule is about ^fo inch in diameter 

 and IS convoluted. When the coils are undone the tubule measures about 

 2 teet m length. The tubules of each lobule unite into one and the tubules 

 of adjacent lobules unite in turn, and so give rise to the tuhuli recti, each of 

 which IS about ^i^y inch m diameter, and about -^\ inch in length These 

 tubuh recti enter the mediastinum, where they form by their division a net- 

 work, called the rete testis. From this rete tubules, called vasa efferentia 

 proceed, which are about ^V inch in diameter, their number varying from 

 twelve to twenty. These leave the testis at the upper part of its posterior 

 border. For a short distance thereafter they remain straight, but they 

 are soon thrown into convolutions, which form conical masses, called coni 

 vasculost. The length of each conus vasculosus is about ^ inch and its 

 apex IS directed towards the testis. When the convolutions are undone the 

 tube assumes a length of about 8 inches, its diameter gradually diminishing 

 from about A inch at its commencement to about ^\ inch at its termination 

 Ihe com vasculosi open by separate orifices into the canal of the epididymis. 



Globus Major 

 Coni Vasculosi 



Body of Epididymis 



Vas Deferens 



, Mediastinum Testis (Corpus 

 Highmorianum) 



L.LobuIus Testis 



■"•Tunica Albuginea 



Vas Aberrans 



Globus Minor 



Fig. 296. — The Structure of the Testis and Epididymis. 



The epididymis consists of one tube, having a diameter of about 

 iV inch in the globus major, where it commences in a blind extremity. 

 In the body it diminishes a httle in diameter, and in the globus minor 

 it again enlarges. The tube presents a great number of convolutions, 

 which, being folded upon themselves and connected together by loose tissue, 

 give rise to a series of lobules. When the convolutions are undone the 

 length of the epididymis has been variously estimated at from 12 to 20 feet. 

 At its upper extremity it receives the coni vasculosi, and beyond the globus 

 minor it terminates in the vas deferens. At the point where it terminates 

 in the vas deferens there is a diverticulum connected with it, called the 

 vas aberrans of H alter, which extends upwards in a convoluted manner between 

 the epididymis and the adjacent part of the vas deferens. The vas aberrans, 

 when the coils are undone, is from 8 to 1 2 inches in length. 



Minute Structure. — The tubuli seminiferi are composed of a hyaline base- 

 ment membrane, lining which there are several layers of epithelial cells, 

 (i) The most external layer consists of cubical cells, known as the parietal 

 cells. They line the basement membrane of the tubule, and are of two kinds. 

 The majority of them give rise to the spermatozoa, and these are called the 

 spermatogenic cells, or spermatogonia. Others arc of a supporting nature, 

 and are called the sustentacular cells, or cells of Sertoli, which subsequently 



