436 



COMPARATIVE ANATOMY 



of a glomerulus into the Bowman's capsule. Arterial and venous con- 

 nexions are subsequently established similar to those of the mesonephros. 

 These changes occur in the later months of intra-uterine life. (Fig. 365) 



mth 



Fig. 361. — Profile reconstructions of lizard {Lacerta agilis) {A) i6 mm. long; {B) 

 20 mm. long; and (C) huinan embryo 115 mm. long, a, allantoic stalk; c, cloaca; cc, 

 cranial collecting tubule; cd, caudal collecting tubule; k, permanent kidney (meta- 

 nephros) ; met, median collecting tubule; ms, mesonephros; ml, metanephric (nephro- 

 genic) tissue; mtb, mesonephric tubules; pet, primary collecting tubule; pii. Wolffian 

 duct (primitive ureter); r, rectum; s, secondary collecting tubule; u, ureter; cm, u and 

 pu, common portion of primitive and permanent ureters. (From Kingsley's " Com- 

 parative Anatomy of Vertebrates," after Schreiner.) 



TERTIARY COLLECTING TUBULES 



SECONDARY 

 COLLECm NG 

 TUBULES '^'^ 



'PELVIS 



Fig. 362. — The anterior expanded portion of the ureter in a 20 mm. embryo showing 

 the beginning of formation of collecting tubules. Anterior is to the right. (Redrawn 

 after Huber.) 



Connexions with the Bladder. During the earlier stages of its devel- 

 opment, each ureter shares with a mesonephric duct a common lateral 

 opening into the cloaca. Between lo mm. and 17 mm. stages, the cloaca 

 becomes divided by a septum into a dorsal rectum and a ventral urogenital 



