272 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



Transitional 

 epithelium. 



bladder is loosely attached to the muscular is, and is 

 slightly corrugated or folded in the contracted form 

 of the organ. At the lower part of the bladder is 

 found the orifice leading into the urethra, and im- 

 mediately behind this is a smooth triangular surface 

 called the trigone. The orifices of the ureters are 

 found at the posterior angles of the trigone, and in 

 the distended bladder are about one and one-half 

 inches apart and about the same distance from the 

 urethral orifice. When the bladder is contracted 

 this space is diminished. An exact knowledge of 



these relations 

 is important in 

 any attempt to 

 pass a catheter 

 into the ureter. 

 Histology o f 

 the Bladder- 

 There is a mu - 

 cous, submu- 

 cous, muscular, 



and serous coat to the bladder. The mucous mem- 

 brane resembles that of the ureters, with which it is 

 continuous. It is covered with a transitional epithe- 

 lium whose cells vary according to the distention of 

 the bladder. As a rule, epithelial cells have but very 

 little elasticity and mucous membranes, therefore are 

 frequently much folded . The bladder cells are capable 

 of considerable distention, when they become very 

 flat. When the organ contracts they accommodate 

 themselves to this condition and become cubical. The 

 cells of the surface layer are squamous and have 



Fig. 205. Section through the mucosa of the 

 bladder. 



