THE UROGENITAL SYSTEM. 



109 



of the kidney are formed from groups of epithelial cells on 

 the convex margin of the dilated end of the renal bud. 

 They arise as tubular buds which grow out into the intermediate 



mesoblast 

 lomeruli, etc. 



collect tubules 

 calix 



i ureter, stalk 

 { of bud. 



Wolffian duct. 



y. -r ureter opening 

 ti-4. in bladder 



j urogenital sinus 

 [ (from cloaca) 



rectum 

 genit. tub. 



cloaeal memb. 

 perineal dep, 



cauda 



Ftg. 84. — The Termination of the Ureter in the Bladder and Sub-division of the 



Renal Bud. 



cell mass, subdividing as they grc 

 spring out in groups, each group 



out. 



forming 



inter- 



at its 



mass, 



The 



The tubular buds 

 pyramid. The 

 tubules at first are straight, but as they grow into the 

 mediate cell mass, each tubule becomes convoluted, and 

 blind end a glomerulus, formed in the intermediate cell 

 is developed and comes to project within the tubule, 

 glomeruli, and perhaps also the convoluted tubules, are produced 

 from the renal mesoblast beneath the capsule, batch after batch 

 being formed as the kidney grows. The loop of Henle is late in 

 appearing. Thus it will be seen that the ureter, the pelvis of the 

 kidney and at least the collecting tubules of the kidney are 

 derived from the epithelial bud which springs from the Wolffian 

 duct ; the capsule of the kidney, the intra-renal connective tissue, 



