DESCENT OF THE TESTICLES 



199 



and upper Wolffian fold become the suspensory ligament of the ovary enclosing 

 the ovarian vessels. The lower genital fold, and the plica gubernatrix develop 

 involuntary muscular fibres and become the ovarian and round ligaments respec- 

 tively. In the male the primitive relations are more departed from, owing to the 

 descent of the testicle, and are further modified by the disappearance of the 

 Miillerian ducts. The Wolffian mesentery, the genital mesentery, and the 



genital gland 



Wolffian 

 body 



allantois 



diap hragmatic 



fold 



cranial genital 



fold 



urogenital fold 



* caudal genital 



fold 



plica gubernatrix 



FIG. 251. THE PERITONEAL FOLDS CONNECTED WITH THE WOLFFIAN BODIES AND GENITAL GLANDS 

 OF A PIG-EMBRYO OF 6'7 CM. LONG. (After Klaatsch.) 



urogenital fold are merged in the different portions of the adult mesorchium, but 

 leave no trace within the abdomen. The plica gubernatrix, which after the atrophy 

 of the Wolffian body is continuous with the Wolffian and genital mesenteries, 

 becomes the gubernaculum testis. The testis descends to the iliac region in the 

 third month, but only enters the internal abdominal ring in the seventh month. 

 Previously to this a pouch of peritoneum the processus vaginalis has descended 

 into the scrotum along the abdominal ring, pushing before it part of the internal 



FIG. 252. DIAGRAMS TO ILLUSTRATE THE DESCENT OF THE TESTICLE AND THE FORMATION 

 OF ITS COVERINGS. (O. Hertwig.) 



In A the testicle is lying close to the internal abdominal ring. In B it has passed into the sac of 

 the tunica vaginalis. 1, skin of abdomen ; 1', skin of scrotum ; 2, superficial abdominal fascia ; 

 2', Cooper's fascia ; 3, muscular and aponeurotic layer of abdominal wall ; 3', cremaster muscle and 

 spermatic fascia; 4, peritoneum; 4', processus vaginalis; 4", visceral layer of processus vaginalis 

 covering testicle ; t, testicle ; v.d., vas deferens ; r, internal abdominal ring. 



oblique muscle and the aponeurosis of the external oblique, which form respectively 

 the cremasteric muscle and spermatic fascia (fig. 252). This pouch, after the descent 

 of the testicle into it, becomes shut off from the abdominal cavity, and forms the 

 cavity of the tunica vaginalis. The descent of the testicle into the scrotum is 

 intimately connected with changes in the gubernaculum. The gubernaculum 

 extends from the integument of the groin, which afterwards forms the scrotum, 



