Final Flashcards
what arises from the intermediate mesoderm
kidneys, gonads, and adrenals
what arises from the lateral plate mesoderm
heart, blood vessels, body cavity, and pelvic/limb skeletons
BMP levels of intermediate and LMP (induced)
high, further from the neural tube and notochord results in less BMP inhibitors and more BMPs, possibly as a result of differential expression of Fox genes
Pax2
specifies intermediate mesoderm
nephron
functional unit of the kidney
development of the kidney
occurs in 3 stages through reciprocal interactions, only the last stage is the final functional kidney
stages of development of the kidney
formation of the pronephros, mesonephros, and then metanephros
formation of the pronephros
pronephric duct cells migrate and induce the formation of pronephros, tubules of the initial kidney, which eventually results in the Wolffian duct
formation of mesonephros
grow out of the Wolffian duct in the posterior region
formation of metanephros
arises from the metanephric mesenchyme at the most posterior region of intermediate mesoderm, which induces branching and the formation of Ureteric buds
what specifies the identity of the kidney?
BMP levels and interaction of the paraxial mesoderm, which induces Lim1, Pax2, and Pax8 (which will induce kidneys in other mesoderm cells)
what limits the position of kidney formation?
Hox genes, give competence to respond and express Lim1
which interactions result in the final kidney development?
reciprocal interactions between the ureteric buds, which become collecting ducts and ureter, and the metanephric mesenchyme, which becomes the nephron. Ureteric bud branches into the metanephric mesenchyme, which then condenses and forms the nephron
how do the different cell populations arise?
differences in the time they migrated through the primitive streak
migration that results in Ureteric cells
early migration lead to less time exposed to Wnt and more time exposed to posterior FGF9 and RA, so those are high and Wnt is low
migration that results in metanephric mesenchymal cells
late migration results in longer exposure to Wnt (higher levels) and lower levels of FGF9/RA, low FGF9 and RA levels make the tissues competent to respond to the signals of the Ureteric bud
mechanisms of the reciprocal induction that forms the kidneys
- Metanephric mesenchyme signals the ureteric bud to branch off the Wolffian duct through GDFN secretion
- Ureteric bud signals the mesenchyme to survive by preventing apoptosis through secretion of Fgf2, Fgf9, and BMP7, results in a population of stem cells
- Mesenchyme induces the UB to branch further and further, creating ureteric bud tip cells and mesenchyme cap cells
- UB induces the mesenchyme to condense and develop the nephron, bud cells release Wnt signals which triggers MET in condensed cap cells, epithelium undergoes morphogenesis and tubulation to form kidneys
GDNF
glial-derived neurotrophic factor (GDNF) that gets secreted from the metanephric mesenchyme and causes outgrowth of the ureteric bud
which signaling factor is necessary for the MET for mesenchyme cells in the kidney
Notch (Wnt)
connection of ureter to bladder endoderm
to complete the filtration system, the ureter uses Eph-ephrin pathway to find the bladder
location of the LMP
furthest from the notochord/NT, lateral to the intermediate mesoderm
layers of the LMP
dorsal side is somatic mesoderm, ventral is splanchnic mesoderm, space between them becomes the coelom
development of the circulatory system
first functional system to develop in the embryo, arising from the splanchnic (ventral visceral) mesoderm
development of the heart
starts in left and right regions which later merge, heart progenitor cells migrate together through the primitive streak and then anteriorly to join the LPM creating the heart fields (cardiogenic mesoderm)
first heart field
forms the scaffold of developing heart as well as the left ventricle, expressing Mesp1 and Nkx2.5
second heart field
forms the rest of the heart as well as jaw muscles and lung mesenchyme, expressing Mesp1, Nkx2.5 AND Tbx1