Organogenesis Flashcards
Kidney origins?
Wolffian duct extends whole way through bod, from shoulders. pronephrons degen first. mesonephrons degen next in mammals (maintained in birds). WE KEEP METANEPHRIC KIDNEY
Fish/amphibia filtration??
primitive, related to pronephrons.
How is kidney formation first induced?
nephrogenic mesenchyme next region uteric bud will form, expresses transcription factors HOX a11, c11, d11. Condensing mesen, secretes GDNF. signals to wolffian through ret transmembrane receptor, induce outgrowth of uteric bud.
how is metanephric mesen kept alive
reciprocal signalling: ureteric bud secretes BMP7 and FGF2. both prevent mesen apoptosis. FGF2 promotes further mesen condensatipon and expression of WT1. WT1 absence causes mesen death.
what prevents ureteric bud formation forming in wrong places?
other mesen apart from the one secreting GDNF, secretes BMP4. prevents ureteric bud formation.
what happens if BMP4 is inactivated?
production of ectopic ureteric buds. this could lead to multiple kidneys that fuse together. diseases.
what induces mesen to tubule (epithelial) formation?
Secretion of prots Wnt9b and LIF.
how does the kindey form multiple nephrons?
Branching morphogenesis.
What induces branching morphogenesis?
mesen induces ureteric bud to branch by secreting GDNF and TGF beta1. GDNF promotes branching, TGF b1 stabilizes branches. Wnt11 maintains GDNF (reciprocal)
how does nephron formation begin?
condenses mesen secretes Wnt4, which singals to cells that make it to start forming nephron.
what are the 4 cell types of glomerulus?
Capillary endothelium, podocytes, parietal epithelium and mesangial cells.
glomerulus formation?
cells at furthest end of S body differentiate into podocytes. these secrete VEGF which attracts endothelial cells. forms capplieries. together secrete glomeruler basement membrane.
what does sprouty1 do?
cytoplasmic protein that antagonises ret signalling during kid induction. ensures single ureteric bud formation only where most GDNF.
