Urinary System 1 Flashcards
What does the paraxial mesoderm give rise to?
Somites
What lies between the somites and lateral plate mesoderm?
A mesoderm component call intermediate mesoderm
What is derived from the intermediate mesoderm?
Urinary Systems
Reproductive Systems
What does the paraxial mesoderm induce?
Paraxial mesoderm induces kidney-forming ability of the intermediate mesoderm
What are the three transcription factors that drive nephric tubule development?
Lim1
Pax2
Pax8
Where are Lim1, Pax2 and Pax8 expressed?
In the intermediate mesoderm which lies between the somites and the lateral plate mesoderm
What has occured upon evolution from lower forms to higher forms?
Development complexity of the kidney and its functional efficiency have vastly increased
How does the urinary system develop?
In an organized fashion involving “generations” of nephric tubules
What is the 1st generation of nephric tubule development?
Development in the cervical region of the embryo - representing the -pronephros
What is the second generation of nephric tubules?
Development in the thoraco-lumbar region representing the -mesonephros
What is the 3rd generation of nephric tubules?
Development in the sacral region representing the
-metanephros
Of the 3 generations what is the most functional capable structure?
Metanephros
What occus as the most caudal metanephros develops and becomes functional?
The pronephros and mesonephros atrophy
What occurs at approximately time of somite development?
Cells of intermediate mesoderm in cervical region give rise to inner visceral layer and outer parietal layer.
What is the cavity formed between inner visceral layer and outer parietal layer?
Nephrocele
What are nephrotomes?
Cords of cells that grow out from parietal (dorsal) wall and form pronephric tubules
What occurs at the distal end of each pronephric tubule?
Grows and extends laterally then moves caudally to fuse with same region of growing cells of the tubule right behind it
What is the pronephric duct?
Site where distal end of each successive tubule fuses
What occurs as more pronephric tubules form?
They fuse with the ever growing duct
THe duct grows toward the cloaca and becomes canalised (duct is initially solid)
What does first glomeruli start as?
Starts as tufts of capillaries branching from dorsal aorta in pronephros
Tufts push and invaginate into wall of pronephric tubule to form intermal glomeruli
What is Bowmans Capsule
Invaginated epithelium around each glomerulus
Funciton of internal glomerulus
Filtration producing a flitrate that moves to the pronephric tubule
Water and electrolytes are re-absorbed and waste products move to the pronephric duct then cloaca
What is the urogential ridge?
Proliferation of intermediate mesoderm in the thoraco-lumbar region and projects into the peritoneal cavity
When does the urogenital ridge begin to form?
Post-somite stage of development
What develops around each mesonephric tubule?
Peri-tubular capillar network
What does the peri-tubular capillary network aid in?
Greater capability of reabsorption of water and electrolytes
How does mesonephros differ from pronephros?
Greater size
Pronephros - one tubule at level of each somite
Mesonephros - multiple mesonephric tubules at each somite
What supplies blood to mesonephros and pronephros?
Dorsal aorta
What two structure give rise to the metanephros form of the excretory organ?
Ureteric bud - outgrowth of mesonephric duct
Region of Urinary ridge - Metanephric mass
Where does development of metanephros take place?
Sacral region of the embryo
What induces metanephric tissue to give rise to metanephric tubules?
Collecting ducts
What influences final arrangement of kidney in mammals?
Manner in which widened end of ureteric buds develop
What is the metanephric blastema or mass composed of?
Mesenchyme
What is needed for survival of metanephric mesenchyme?
Ureteric bud
What does GDNF do?
GDNF = Glial-derived neurotrophic factor
- Secreted by mesenchyme and stimulates bud to become highly branched
What do Wnt6 and Wnt 9b do?
Induce mesenchyme to form tubular epithelium which will be part of tubule
What is the comma part of the tubule formation part of?
Develops into podocytes
Function of podocytes?
Secret VEGF (vascular endothelial growth factor)
- VEGF induces capillaries to branch and future formation of glomerulus
