776 EMBRYOLOGY 



usually hanging a little lower than the right. The coverings for each 

 testicle, in addition to those just mentioned, are the intercolumnar fascia, 

 the cremaster muscle, the infundibuliform fascia, the tunica vaginalis and 

 the proper fibrous coat. 



The tunica vaginalis is a closed sac of serous membrane, covering 

 the testicle and epididymis and reflected from the posterior border of the 

 testicle to the wall of the scrotum, lining the cavity occupied by the 

 testicle on either side and also extending over the spermatic cord. 

 This tunic is a process of peritoneum that has been shut off from 

 the general lining of the abdominal cavity. The spermatic cord is 

 composed of the vas deferens, bloodvessels, lymphatics and nerves, 

 with the coverings already described, which expand and surround the 

 testicle. 



Beneath the tunica vaginalis are the testicles, with their proper 

 fibrous coat. These organs are ovoid and flattened laterally and 

 posteriorly. "They are an inch and a half to two inches (38.1 to 50.8 

 millimeters) long, about an inch and a quarter (31.8 millimeters) from 

 the anterior to the posterior border, and nearly an inch (25.4 millimeters) 

 from side to side. The weight of each varies from three-quarters of an 

 ounce to an ounce (21.2 to 28.3 grams), and the left is often a little the 

 larger of the two " (Quain). The proper fibrous coat is everywhere 

 covered with the closely-adherent tunica vaginalis, except at the posterior 

 border, where the vessels enter and the duct passes out. At the outer 

 edge of this border, is the epididymis, formed of convoluted tubes, pre- 

 senting a superior enlargement, called the globus major, a long mass 

 running the length of the testicle, called the body, and a smaller, in- 

 ferior enlargement, called the globus minor. This too is covered with 

 the tunica vaginalis. Between the membrane covering the testicle and 

 epididymis and the layer lining the scrotal cavity, is a small quantity of 

 serum, just enough to moisten the serous surfaces. At the superior 

 portion of the testicle are one or more small ovoid bodies, called the 

 hydatids of Morgagni, each attached to the testicle by short constricted 

 processes. These have no physiological importance and are supposed 

 to be the remains of foetal structures. 



The proper fibrous coat of the testicle is called the tunica albuginea. 

 It is white, dense, inelastic, measures about -^ of an inch ( I millimeter) 

 in thickness, and is simply for the protection of the contained structures. 

 Sections of the testicle, made in various directions, show an incomplete 

 vertical process of the tunica albuginea, called the corpus Highmor- 

 ianum, or the mediastinum testis. This is wedge-shaped, about -J- of an 

 inch (4.2 millimeters) wide at its superior and thickest portion, is pierced 

 by a number of openings and lodges bloodvessels and the seminiferous 



