Changes

==The Kidneys==

==The Kidneys==

[[Image:dev1tri.jpg|right|thumb|300px|<small><center>A schematic showing the early development of the pro, meso and metanephros</center></small>]]

[[Image:dev1tri.jpg|right|thumb|300px|<small><center>A schematic showing the early development of the pro, meso and metanephros</center></small>]]

[[Image:dev2tri.jpg|right|thumb|300px|<small><center>A schematic showing the later development of the mesonpehros and metanephros after the regression of the pronephros. At this point the pronephric duct is now more appropriately called the mesonephric duct</center></small>]]

[[Image:dev2tri.jpg|right|thumb|300px|<small><center>A schematic showing the later development of the mesonpehros and metanephros after the regression of the pronephros.</center></small>]]

The kidneys are formed from the intermediate mesoderm.  Firstly it begins to thicken longitudinally in its caudal domain.  This is called the nephrogenic thickening.  From this thickening three so called attempts at producing excretory origins arise.  All the attempts have at the histological level a series of excretory tubules however only one of these attempts forms the kidney in adult life.

The kidneys are formed from the intermediate mesoderm.  Firstly it begins to thicken longitudinally in its caudal domain.  This is called the nephrogenic thickening.  From this thickening three so called attempts at producing excretory origins arise.  All the attempts have at the histological level a series of excretory tubules however only one of these attempts forms the kidney in adult life.