Urinary System development Flashcards
What is the function of the pronephros in mammals?
-non-functional and the pronephros tubules are solid cords, but it is required in order for the rest of the excretorye system to develop
In what organisms is the pronephros functional?
-fish and amphibians
Describe the development structure of the pronephros.
- each pronephros consists of 7 nephrons
- each nephron develops from a single somite, from a region of the somite called the nephrotome
- these amniote pronephric tubules are solid
- laterally they are connected to a longitudinal duct called the pronephric duct
What is the pronephric duct?
- duct extends from the pronephric tubules through the mesonephric ridge caudally to the cloaca
- two pronephric ducts, one on each side
- the pronephric duct will be renamed the mesonephric duct
What induces the pronephric ducts?
RA -> Hox 4-11 genes -> Pax-2 and Pax-8 -Lim-1-> aggregation of mesenchymal cells in intermediate mesoderm into pronephric ducts
In lower vertebrate embryos the proximal ends of the pronephric tubules open into the __________ cavity.
Coelomic
What is the highly vascularized ridge that runs along the mesonephric ridge called?
-glomus
What does the globus do?
- small molecules from the blood are filtered from the capillaries into the glomus into the Coelomic cavity
- from the coelom these materials move into the openings (nephrostomes) of the pronephric tubules and from there to the pronephric duct to the cloaca
Where does the mesonephros develop? Is it a functional kidney?
- caudal to the pronephros
- functional kidney in most vertebrate embryos, including humans
- in salamanders the cranial part of the mesonephros does not function in the adult kidney -> functional is referred to as opisthonephros
Describe the structure of the mesonephros.
- consists of mesonephric tubules that are longer than pronephric tubules and are often sigmoid or convoluted
- about 70 pairs of mesonephric tubules
- do not open into the coelom -> enclosed within expanded, double walled saclike invaginations of the proximal ends of then tubules
Describe the structure of the nephrons in the mesonephros.
- cup like pockets called renal corpuscles
- enclosed capillary aggregations called glomeruli
- the mesonephric glomeruli are enclosed within the renal corpuscles, the vascular filtrate bypasses the coelom and goes directly into the nephron
What do the distal. Ends. Of. The mesonephric tubules form?
- do not form their own excretory ducts
- they connect with existing pronephric ducts
- pronephric ducts are then renamed the mesonephric ducts/Wolffian ducts
After the mesonephric tubules begin to function, the pronephric tubules/cords _________.
Degenerate
The development of the mesonephric tube is dependent on the presence of what?
-pronephric duct
What regulates the transformation of the intermediate mesenchyme to epithelium?
WT-1
Just before the mesonephros attaches to the cloaca what happens? Why is this significant?
- mesonephric duct develops an evaginations called the uterus bud
- uterus bud initiates a series of inductive interactions that will result in the formation of the final kidney -> metanephric kidney
What structure gives rise to the adult ureter, renal pelvis, and collecting tubules?
-metanephric diverticulum
What does the metanephric. Diverticula induce?
-formation of the metanephrogenic blastema
What does the metanephrogenic blastema do?
- will form the renal tubules of the adult kidney
- have a reverse inductive effect on the ureteric diverticula
- neither can continue to develop in the absence of the other
Review the development of the metanephros in screen shots.
:)
How do the utereric buds branch?
-GDNF from metanephrogenic mesenchyme
-causes tips of ureteric buds to
+produce FGF-2 and leukemia inhibitory factor
+induce surrounding metanephrogenic mesenchyme to form epithelial precursors of renal tubules
What is the first kidney to develop?
Pronephros At 22 days of gestation
