Anatomy Flashcards
(25 cards)
Induction in Limb development and factors regulating it
Early Limb bud begin with activation of mesenchymal cells in lateral mesoderm
Regulated by wnt protein and Fibroblast Growth factor
pattern formation
Set of processes by which embryonic cells form ordered spatial arrangements of differentiated tissue
three axes(Dimensions) in which limb bud differentiation occurs
- Proximal-distal axis-shouldeer-finger ;hip-toe
- anterior-posterior axis-thumb -anterior;little finger -post
- Dorsal -Ventral Axis Palm-ventral ;Knuckles -dorsal
early stages of limb development controlled by which gene
Homeobox gene
Limb Buds Form Deep Thick band of ectoderm of the surface known as
apical ectodermal ridge
Epithelial -Mesenchymal Interactions?
AER induced by underlying mesenchyme
Bone morphogenic protein signals Fibroblast growth factor(induction and maintenance of AER)
-Wolffian( mesonpheric) duct-drains primitive kidney
AER induces Limb mesenchyme that initiates growth and development of limbs in proximal distal axis -fgf responsible
Zone of polarising activity
Mesenchymal cells aggregate at the posterior margin of the limb
State and explain the use of enymes and genes i the zone of polarizing activity
FGF from Apical ectodermal ridge activate the ZPA to express hedgehog(ssh) genes
ssh gen secretes control patterning of limb along anterior posterior axis
Progress zon
Stimulated mesenchymal cells by fgf that proliferate
What helps develop anterior posterior axis
Shh secretons from sonic hedghog gene result in patterning of limb
Proteins involved in development of dorsal ventral axis
Dorsal epidermis of limb bud expresses Wnt7
Ventral aspect expresses engrailed -1(EN-1)
Mesenchyme proximal to AER differentiate into
Blood Vessels
Cartilage Bone Model
Distal end LImb buds flatten into paddlelike
Handplates
Footplates
End of week 6
End of week 7
Mesenchymal Tissue in handplate condensd into digital ray
Mesenchymal Tissue in footplates condense into didgitl rays and toes
Mesenchymal Pirimordia
Aer at the tip of each digital ray induces development of mesenchymal primordia of bones (phalanges)
Bone Morphogenic protein(BMP) AND Transforming growth factor(TGF)
USE
Apoptosis of interdidgital regions tissue
Whats needed in joint formation in apoptosis
BMP7 PROMOTES cartilage formation
BMP2 Forms joints (expressed between bones
Wnt Protein and blood vessels for joint development
Week 7
Week 6
Week 5
Osteogenesis of long bones
Entire skeleton Cartilaginous
Chondrofication centres appear
use of somites
In week 5 myogenic precursors from dermomyotome of somites migrate to limb buds and differentiate to form myoblasts to form
dorsal mass-extensor and abductors
ventral mass-flexor and adductors
when do nerve interventions develop
week 5 peripheral nerves grow from developing limb plexus
Position of neural tube affected by?
Growth cone
Dorsal Branches of ventral rami innervate?
dorsal masses -islet2 and lim1
ventral branches innervate which muscle derivate
ventral mass islet 1 and islet 2
neural growth hormone pathfinding mechanism
neurotrophin
chemotaxis
substrate guidance
cell-cell recognition
