Changes

==Lower Urinary Tract==

==Lower Urinary Tract==

The separation between the termination of the digestive and urinary tracts on the outer surface of the body is not always the case.  In fact the urinary tract comes from the horizontal division of the primitive hind gut in the cloacal region.  This separation is done by a wedge of mesoderm called the urorectal septum.  This wedge is located between the hindgut and the allantoic bud.  The wedge grows until it reaches the cloacal membrane and has thus then divided the original hindgut into dorsal (anal) and ventral (urogenital) parts. The divide is termed the perineal body.  The cloacal membrane covering the urogenital opening then breaks down forming the urogenital passage.  This passage splits in cranial and caudal parts with the cranial part comprising the bladder and eventually the allantois and the caudal part comprising the urethra.

The urinary tract comes from the horizontal division of the primitive hind gut in the cloacal region.  This separation is done by a wedge of mesoderm called the urorectal septum.  This wedge is located between the hindgut and the allantoic bud.  The wedge grows until it reaches the cloacal membrane and has thus then divided the original hindgut into dorsal (anal) and ventral (urogenital) parts. The divide is termed the perineal body.  The cloacal membrane covering the urogenital opening then breaks down forming the urogenital passage.  This passage splits in cranial and caudal parts with the cranial part comprising the bladder and eventually the allantois and the caudal part comprising the urethra.

===The Bladder===

===The Bladder===