2042 



HUMAN ANATOMY. 



Peritoneum 



,Vas deferens 

 ' Deep epigastric vessels 



Sac of I 

 processus vaginalis 



Peritoneum -1- 



Tunica vaginalis -r 

 communis 



Cremaster 



Intercolumnar 

 fascia 

 Skin and dartos 



testicle, which, drawn from its mesentery (mesorchium), descends outside and behind 

 the peritoneal pouch that later constitutes its partial serous investment, the tunica 

 vaginalis. After the descent, is completed, usually shortly before birth, but some- 

 times not until afterward, the tubular 

 Fig. 1722. upper segment of the peritoneal sac 



closes normally during the early months 

 of childhood. This closure takes place 

 first in the vicinity of the internal ab- 

 dominal ring and in the middle of the 

 tube, passing upward towards the ring 

 and downward to within a short distance 

 of the sexual gland. The occluded 

 portion of the vaginal process is later 

 represented by a small fibrous band ilig- 

 ameyitum vaginale) that extends from the 

 internal abdominal ring above, through 

 the inguinal canal and for a variable dis- 

 tance down the spermatic cord, some- 

 times, although not commonly, as far as 

 the tunica vaginalis. When the pro- 

 cessus vaginalis fails to close, as it oc- 

 casionally does in man and always in 



Vas deferens 



Epididymis 



Testis 



Scrotal 

 ligairlent 



descended testicle to 



Diagram showing relations 

 processus vaginalis, which still freely communicates with 

 peritoneal sac of abdomen. {After IValdeyer.) 



certain animals, as the rat, in which de- 

 scent and retraction of the testis periodically occur, the serous sac surrounding the tes- 

 ticle communicates throughout life with the peritoneal cavity, a condition favorable to 

 the production of hernia. With the obliteration of the lumen of the processus vaginalis, 

 an inguinal canal, in the sense of a distinct tube, disappears, the spermatic duct and 

 associated vessels and nerves, that necessarily share in the migration of the sexual gland 

 into the scrotum, passing between the muscular and fascial layers of the abdominal wall 

 embedded in connective tissue. The remains of the shrunken genito-inguinal liga- 

 ment, or gubernaculum, are represented by a fibro-muscular band, the scrotal liga- 

 ment, that connects the lower end of the epididymis to the scrotal wall (Fig. 1650). 

 Descent of the testicle may be imperfectly accomplished, so that the gland, failing 

 to reach the bottom of the scrotal sac, may be arrested within the inguinal canal or 

 spermatic cord, or permanently retained wuhin the abdomen, a condiiion known as 

 cryptorchism, usually leading to atrophy of the gland. Associated with faulty descent 



may be anomalous situation, the testis 



Fig. 1723. 



Peritoneum 



Vas deferens 



Deep epigastric vessels 



Closed portion of 

 processus vaginalis 



Epididymis 



lying beneath the integument near the 

 external abdominal ring, in the thigh, or 

 in the perineum. After descent the axis 

 of the testicle may be abnormally di 

 rected, the gland assuming a transverse, 

 rotated, or even inverted position. 



DifTerentiation of the Female 

 Type. — Development of female internal 

 reproductive organs proceeds along the 

 same lines as in the male, the ovary being 

 differentiated from the indifferent sexual 

 gland and the genital canals from the 

 Miillerian and Wolffian ducts. 



Differentiation of the ovary has been 

 described in coiinection with that organ 

 (page 1993). That of the Fallopian 

 tubes, uterus, and vagina results from 

 further growth, fusion, and modification 

 of the Miillerian ducts. Lower segments 

 of the latter, below the attachment of the ligament of the ovary (page 2040), undergo 

 fusion and form the uterus and vagina. Their upper segments remain unfused and be- 

 come Fallopian tubes. Details of these changes are given under the respective organs. 



Crema,ster 



Tnfundibuliform fascia 

 Sac of tunica vaginalis 



Visceral layer 

 Parieta 



Skin and dartos 



estis 



-4 Scrotal 



ligament 



Diagram showitig relations of testicle to serous mem- 

 brane after upper part of )irocessus vaginalis has closed, its 

 lower part persisting as tunica vaginalis. 



