1056 



URIXAnV AXD REPRODUCTIVE ORGANS 



tenth week, and tlien continues to increase, becoming con side rablj' the greater by the end of foetal 

 Hfe ; but even at birth the suprarenal bodies are proporti<jnally much hirger thau in the adult. 



The urinary bladder apjK'ars in the second month as a transformation of the pedicle of the 

 allantois, a structure whicli has already done service in conveying the vessels of the embryo to 

 the placenta. The allantois is a hypoblastic sac invested by a layer of mesoblast, and communi- 

 catinff with the liind trut. That 'portion of it which lies within the body becorues dilated at its 

 central part into the urinarv bladder, but remains narrow at both extremities, forming in front 

 the urachus ; and behind, "tlie whole urethra in the female, and the upper part of the pros- 

 tatic urethra in the male. , TTT ,«> -1 ^ n 1 • 1 



The generative ai)i>aratus is developed from the Wolffian ducts and trora two other paired 

 structures closely related to these, but of somewhat later Ibrmation — the Miillerian ducts and the 



genital glands. , . , ,. i • i •, ■, ^ ^ n ^ 



From the Wolffian body its tubules and its duct are tormed, in the male, the whole ot the 



Fig 64.5 —Development of the Ueixo-gexerative Organs, Female Type. 



(After Henle.) 



(The parts formed from the Miillerian duct in this and the succeeding diagram are 



indicated by horizontal shading ; those formed from the Wolffian 



body and duct, by diagonal cross-hatching.) 



FALLOPIAN TUBE 

 PAROVARIUM 



Bound ligament 



CRUS CLITORIDIS 



BULBUS VESTIBUU 

 VULVAR CLEFT 



URETHRA 



GLAND OF BARTHOLIN 



CLITORIS 



excretory tubes outside the body of the testicle, namely, the vasa efferentia, the coni vasculosi, 

 the tube of the epididymis, the vas deferens, the ejaculatory duct, and the paradidymis (the organ 

 of Giraldes). In the female the structure dwindles away, leaving its vestiges as the jiarovarium 

 and the duct of Gartner (the latter being occasionally demonstrable in the human subject). 



The genital gland arises as a ridge, partly mesoblastic and partly due to a thickening of an 

 ei)ithelial layer, the germinal epithelium, on the inner side of the Wolffian bodj'. The cells, at 

 first indeterminate, soon become differentiated to form the Graafian follicles and ova in the female, 

 ami the ei)ithelium of the seminiferous tubes in the male ; the rest of the ovary or testicle being 

 developed from the mesoblast of the ridge. The gland is at first attached to the Wolffian body. 

 Tlie latter is itself fixed to the posterior wall of the abdominal cavity l)y a dujilicature of pei'ito- 

 neum calleil the mesorchium, or mesovarium, from which a little fold containing muscular fibre 

 is prolonged downwards to licconie the gul)frnaculum testis in the male, or, after connection with 

 tlie uterus, the round ligament in the female. 



