788 DEVELOPMENT OF THE WOLFFIAN" BODIES, ETC 



Fig. 296. 



Formation of the TUNICA 

 VAGINALIS TRSTIS. 1. 

 Testicle nearly at the bottom 

 of the scrotum. 2. Cavity of 

 tunica vaginalis. 3. Cavity of 

 peritoneum. 4. Obliterated 

 neck of peritoneal sac. 



which preceded its descent, remains for a time in communication with 

 the peritoneal cavity. In many of the quadrupeds, as, for example, the 

 rabbit, this condition is permanent ; and the testicle may be alternately 

 drawn downward into the scrotum, or retracted 

 into the abdomen, by the action of th& guber- 

 naculum and the cremaster muscle. In the 

 human foetus, the two opposite surfaces of the 

 peritoneal pouch approach each other at the 

 inguinal canal, forming at that point a con- 

 striction, which partly shuts off the testicle 

 from the cavity of the abdomen. By a con- 

 tinuation ot this process, the serous surfaces 

 come in contact, and, adhering together at 

 this situation (Fig. 296, 4), form a kind of 

 cicatrix, by which the cavity of the tunica va- 

 ginalis (2) is shut off from the general cavity 

 of the peritoneum(s). The tunica vaginalis 

 testis is, therefore, originally a part of the 

 peritoneum, from which it is subsequently 

 separated by the adhesion of its opposite 

 walls. 



The separation of the tunica vaginalis testis from the peritoneum is 

 usually completed in the human foetus before birth. But sometimes it 

 fails to take place at the usual time, and the intestine is then liable to 

 protrude into the scrotum, in front of the spermatic cord, giving rise 

 to congenital inguinal hernia. (Fig. 297.) 

 The parts implicated in this malformation 

 have still, as in the case of congenital umbili- 

 cal hernia, a tendency to unite with each other 

 and obliterate the opening; and if the intes- 

 tine be retained by pressure in the cavity of 

 the abdomen, cicatrization usually takes place 

 at the inguinal canal, and a cure is effected. 



Female Organs of Generation. At an early 

 period of development, the ovaries have the 

 same external appearance, and occupy the 

 same position in the abdomen, as the testicles 

 in the opposite sex. The descent of the ovaries 

 also takes place, to a great extent, in the same 

 manner with the corresponding change of 

 When, in the early part of this descent, they 

 have reached the level of the lower edge of the kidneys, a cord, analogous 

 to the gubernaculum, may be seen proceeding from their lower extremity, 

 crossing the efferent duct on each side, and passing downward, to be 

 attached to the subcutaneous tissues at the situation of the inguinal 

 ring. That part of the duct situated outside the crossing of this cord, 

 becomes convoluted, and is converted into the Fallopian tube ; while 



CONGENITAL INGUINAL 

 H K R N i A .1. Testicle. 2, 2, 2. 

 Intestine. 



position of the testicles. 



