THE DEVELOPMENT OF THE UROGENITAL SYSTEM. 



427 



changes that occur in the female. A careful study of the diagrams will assist 

 the student materially in understanding the processes of development which 

 have been described in the preceding paragraphs. 



Below is a table that is meant to set forth briefly the various structures 

 which belong to the internal genital organs in the two sexes, and which are 

 derived from the structures in the "indifferent" stage. The words in- italics 

 are the names of structures that persist in a rudimentary form. 



Indifferent 



Germinal epithelium (meso- 

 thelium) 



Mesonephros \ 



cephalic part < 

 caudal part 



Male 



Convoluted seminiferous tubules 



with spermatozoa 



Straight seminiferous tubules . . 



Rete testis 



Part of stroma of testicle 



Efferent ductules (vasa efferentia) \ 

 Appendage of epididymis . . . J 

 Paradidymis (organ 0} Giraldes) \ 

 Aberrant ductules (vasa aberrantia) / 



Female 



Ovarian (Graafian) follicles 

 with ova. 



Medullary cords. 



Rete cords. 



Part of stroma of ovary. 



Mesonephric duct 



Miillerian duct . 



Inguinal ligament of meso- 1 

 nephros j 



Duct of epididymis (vas epididy- 



midis) 



Deferent duct (vas deferens) ." . 



Ejaculatory duct 



Seminal vesicle . 



Epoophoron, transverse duc- 

 tules. 



Parodphoron. 



Vesicular appendage (of 



Morgagni) (?) 

 Epoophoron, longitudinal 



duct. 

 Gartner's canals. 



Morgagni's appendage of testicle 1 

 (hydatid of Morgagni} . . . / 



Prostatic utricle (uterus masculinus) 



Fimbriae of oviduct. 



Oviduct. 



Uterus. 



Vagina. 



Gubernaculum testis (Hunteri) . 



Urogenital sinus 



Urethra ^ P rostatic P art 1 

 thra \ membranous part . . ] 



Prostate 



Bulbo-urethral gland (Cowpers) 



Ovarian ligament. 

 Round ligament of uterus. 



/ Urethra. 



\ Vestibule of vagina. 

 Prostate. 



Larger vestib alar gland (Bar- 

 tholin's. 



THE EXTERNAL GENITAL ORGANS. 



In addition to the internal organs of generation, to which the description has 

 thus far been confined, certain other structures appear on the outside of the 

 body to form the external genitalia. In the case of these also there is an "indif- 

 ferent" stage from which the courses of development diverge in the two sexes. 



During the sixth week a depression appearing on the ventral surface of the 

 caudal end of the body indicates the position of the cloacal membrane (p. 403) . 

 This becomes surrounded by a slight elevation, produced by the thickening 

 of the mesoderm which is known as the genital ridge (Fig. 381). The cephalic 



