A comparative study of the urinary bladder and the intramural portion of the ureter

Abstract

The bladders belonging to eleven mammalian species were investigated, and as a result the following observations were made: (1) a submucous ureter was found in the case of most of the species examined; (2) histological investigation revealed three types of intramural ureters, and (3) downward extension of ureteric musculature, separate from bladder musculature, to the seminal colliculus in the male, or to the lower end of the urethra in the female, was found. A suggestion is presented to explain the manner by which the ureteric openings change their relations to those of the mesonephric ducts during development. It seems that ‘after absorption of the common segment of the Wolfuan duct, breaking down of the ventral wall of ureter’ is the most likely process.