2l6 



NORMAL HISTOLOGY. 



The muscular tunic consists of loosely connected bundles of unstriped 

 tissue whose continuity as definite sheets is interrupted by often considerable 



intervening fibrous tissue. 

 The muscle-bundles are 

 arranged as a thin and im- 

 perfect longitudinal and 

 a thicker and chief exter- 

 nal circular layer. With- 

 in the renal pelvis and its 

 larger subdivisions, the 

 infundibula, both layers 

 are well represented, but 

 Reflection are reduced on the caly- 



of calyx . i 



onto renal ces, except at the junction 



Renal 



. papilla 



papilla 

 Pelvis 



O f the i atter w i t h t he renal 

 papillae where the circular 

 muscle is augmented and 

 surrounds each papilla 

 with a minute sphincter- 

 like bundle. In the lower 

 half of the ureter, an addi- 

 tional but incomplete ex- 

 ternal longitudinal layer 

 is found outside the cir- 

 cular one. At its end, 

 where the ureter meets 

 and traverses the wall 

 of the bladder, the mus- 



FIG. 267. Longitudinal section through sinus of child's kidney, show- Cular tissue is represented 

 ing lower part of pelvis and commencement of ureter. X 10. ^ most exclusively by a 



-well developed layer of longitudinal fibres, which retain their independence 



Renal 

 blood- 

 vessels 



Ureter 



Epithelium 



Mucous coat 



thrown into 



longitudinal folds 



i^l; 





s &.* 



P''~^ yrv.;::-:v. .- V.'^*,^:^^, 



' 



Fibrous coat 



Outer 



longitudinal 

 muscular 

 bundles 



Circular muscular 

 bundles 



FIG. 268. Transverse section of ureter. X 25. 



and do not blend with the vesical muscle but end in the mucosa of the 

 bladder. Contraction of these fibres tends to dilate the ureteral orifices. 



