Changes

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.

===The Pronephros===

==The [[Developmental_Biology_-_Intermediate_Mesoderm_Development_-_Anatomy_%26_Physiology#Pronephros|Pronephros]]==

This structure forms in the neck region of the embryo and is not functional in mammals.  Its tubules attach and form the continuous pronephric duct.  The caudal edge of this duct then opens into the cloaca.  The duct survives the regression of the tubules and actually helps drain the mesonepohric tubules which begin to appear at this point.

This structure forms in the neck region of the embryo and is not functional in mammals.  Its tubules attach and form the continuous pronephric duct.  The caudal edge of this duct then opens into the cloaca.  The duct survives the regression of the tubules and actually helps drain the mesonepohric tubules which begin to appear at this point.