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Intermediate Mesoderm Development - Anatomy & Physiology (view source)
Revision as of 19:08, 28 June 2012
, 19:08, 28 June 2012no edit summary
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==Introduction==
==Introduction==
The intermediate mesoderm exists as a strip of tissue between the lateral plate mesoderm and somites. It gives rise to the urinary system and some parts of the reproductive system. Kidney development includes three forms:
The intermediate mesoderm exists as a strip of tissue between the lateral plate mesoderm and somites. It gives rise to the urinary system and some parts of the reproductive system. Kidney development includes three forms:
==Pronephros==
==Pronephros==
*''The earliest kidney. Develops in the anterior of the animal (adjacent to somites 7 - 10). Eliminated in later development''.
*''The earliest kidney. Develops in the anterior of the animal (adjacent to somites 1 - 10). Eliminated in later development''.
#At intervals along the intermediate mesoderm, dorsal evaginations occur.
#At intervals along the intermediate mesoderm, dorsal evaginations occur.
#Evaginations extend caudally and eventually fuse with more caudal evaginations.
#Evaginations extend caudally and eventually fuse with more caudal evaginations.
#Capillaries develop at the medial aspect of the intermediate mesoderm so that waste can diffuse from the blood to the excretory channel.
#Capillaries develop at the medial aspect of the intermediate mesoderm so that waste can diffuse from the blood to the excretory channel.
#Connections between the intermediate mesoderm and somites as well between the intermediate mesoderm and lateral plate mesoderm break down.
#Connections between the intermediate mesoderm and somites as well between the intermediate mesoderm and lateral plate mesoderm break down.
==Mesonephros==
*''Development occurs in an anterior to posterior direction; the mesonephros kidney is found at the thoracic to lumbar level''.
#The medial portion of the intermediate mesoderm forms a cup in the region of the capillaries.
#*This is an early Bowman's capsule and improves waste removal.
#The excretory channel pinches off from all surrounding tissue (lateral plate mesoderm) to become entirely closed.
#*Excretory duct now known as the '''Wolffian Duct'''.
*Amphibians and fish use the mesonephric kidney.
==Metanephros==
*''Formation of the metanephros employs recipricol signalling''.
#At the level of the sacrum, a block of intermediate mesoderm breaks off from the Wolffian duct. It is called a '''metanephric blastema'''.
#The metanephric blastema signals to the Wolffian duct.
#*Wolffian duct is induced to grow, and a bud of Wolffian duct moves towards the metanephric blastema.
#*The bud is called the '''ureteric duct'''.
#The ureteric duct contacts the blastema, and divides into two branches.
#One of the branches induces adjacent mesenchyme to undergo a mesenchymal to epithelial transition.
#*It subsequently develops into a nephron.
#The remaining branch splits into two, and repeats the process.
#The primary branch forms the ureter; the remainder leads to the compact kidney of mammals.
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[[Category:Developmental Biology]]
[[Category:Urinary System - Anatomy & Physiology]]