UROGEXITAL SYSTEM. 



nitb 



FIG. 322. Profile reconstructions of lizard (Lacerta agilis) (A) 16 mm. long; (B) 20 mm, 

 long; and (C) human embryo 115 mm. long, after Schreiner. a, allantois stalk; c, cloaca; 

 cc, cranial collecting tubule ; cd, caudal collecting tubule ; k, permanent kidney (metanephros) ; 

 met, median collecting tubule; nit, metanephric (nephrogenous) tisssue; mtb, mesonephric 

 tubules; pet, primary collecting tubule; pu, Wolffian duct (primitive ureter); r, rectum; 

 5, secondary collecting tubule; u, ureter; cm, u and pu, common portion of primitive and 

 permanent ureters. 



FIG. 323. Models of two stages in the development of tubules of kidney (metanephros) 

 of man, after Stoerk. b, Bowman's capsule: r, collecting tubule; en, connecting tubule; 

 cv, convoluted tubule; h, Henle's loop; i, intercalary tubule; /, lower arch; m, middle piece. 



