306 OSWALD S. LOWSLEY 



internal sphincter. Below the verum montanum the urethra 

 becomes more or less star-shaped, indicating a collapsed circular 

 tube. 



Fetus 7.5 cm. long: {thirteen weeks) 



There is considerable change noted in the appearance of the 

 bladder at this stage. Throughout its entire area the wall com- 

 posing the base is thicker than at any other portion of its circum- 

 ference, and the nearer one approaches the trigonal region the 

 greater is the thickness. The musculature of the bladder is dis- 



Fig. 1 5 cm. human fetus two and three-fourths months. Prostatic portion of 

 urethra. 



tinctly made out as deeply staining tissue composed of circular, 

 interlacing and longitudinal strands which are easily differentiated 

 from the connective tissue elements forming the major portion of 

 the bladder wall. The strands of muscular tissue aie much 

 larger and more abundant at the base or inferior portion than at 

 any other. In the region just superior to the trigone where the 

 bas-fond will later develop, the inferior wall is three times as thick 

 as it is at any other part of the circumference. The mucous mem- 

 brane is gathered in folds on the inferior interior surface of the 

 organ throughout its length, while elsewhere it is smooth. 



The trigonum vesicae is about five times as thick as the remain- 

 ing' portion of the vesical wall. The muscular strands composing 



