264 



HISTOLOGY. 



riorly by the elongation of its blind end, it lies in contact with the Wolffian 

 duct as seen in Fig. 299, but the Wolffian duct is said not to contribute 

 toward its formation. The two Mullerian ducts reach the bladder side by 

 side and acquire openings into it, between those of the Wolffian ducts. 

 Near the bladder the two Mullerian ducts fuse with one another so that 

 their distal part is represented by a single median tube on either side of 

 which is a Wolffian duct (Fig. 279, B, page 249). In the female the united 

 portion becomes the vagina and uterus, and the separate parts are the 

 uterine [Fallopian] tubes. In the male the united portion becomes a small 

 blind pocket, the prostatic utricle, opening into the prostatic urethra. 

 Each fimbriated extremity persists in the appendix testis, and the remain - 



FIG. 299. FROM A RECONSTRUCTION OF A 13.6 FIG. 300. DIAGRAM OF THE DEVELOPMENT OF 



MM. HUMAN EMBRYO. (F. W. Thyng.) 



THE TESTIS, BASED UPON FIGURES BY MAC- 



CALLUM AND B. M. ALLEN. 



bl., Bladder; f., fimbriae; g. g., genital gland; 



g. p., genital papilla; M. d., Mullerian duct; c., glomerular capsule; i. c., inner or sex cords; 



p., renal pelvis; r., rectum; ur., ureter; u. s., 

 urogenital sinus; W. d., Wolffian duct. 



M. d., Mullerian duct; o. c., outer or rete 

 cords; W. d., W. t., Wolffian duct and tubule. 



ing portion of the ducts, except for occasional fragments, becomes ob- 

 literated. Thus only the two extremities of the Mullerian ducts are 

 ordinarily permanent in the male (Fig. 301). 



The genital glands in either sex begin as a thickening on the ventro- 

 medial border of each Wolffian body (Fig. 299). A section of this genital 

 ridge is shown in Fig. 276, C, page 245. The ridge is a dense mass of 

 mesoderm covered by the peritonaeal mesothelium which here consists 

 of columnar cells. In forming the testis, cords of cells which later be- 

 come tubules, appear in the dense mesenchyma (Fig. 300). These are 

 considered to be invaginations of the peritonaeal layer rather than segre- 

 gations of mesenchyma. The cords near the surface of the genital ridge 

 become the convoluted tubules of the testis (tubuli contorti) and their con- 



