Limb Development

Question 1

Wnt7a

Answer 1

middle mesoderm, allows for dorsal-ventral patterning of limb. induces Lmx1

Question 2

WNT and FGF

Answer 2

limb bud growth and distalization

Question 3

Nail Patella Syndrome

Answer 3

no nails bc of WNT7a lack

Question 4

Morphogenesis

Answer 4

specific structures arise in specific spaces

Question 5

WNT function

Answer 5

binds to frizzled and LRP to relay signal that transduces via beta catenin, allows activation of transcription of wnt target genes.

Question 6

polydactyly

Answer 6

Shh and hox genes

Question 7

Hox Genes

Answer 7

in hox gene cluster to lead pattern regulations, such as hox 9

Question 8

first step in limb development

Answer 8

establishing a limb forming field

Question 9

syndactyly

Answer 9

fusion of fingies, not good/working BMP

Question 10

human limb (forelimb)

Answer 10

day 24

Question 11

Dorsal and Ventral Ectodoerm

Answer 11

makes WNT7A and BMPs

Question 12

How do FGFs work?

Answer 12

Binds to tyrosine kinase factors

Question 13

homeobox genes

Answer 13

regulation of development

Question 14

what does BMP do?

Answer 14

inhibits limb development, and necrosis in fingies

Question 15

lack of fingies

Answer 15

deletion of Hox 13 gene

Question 16

what do you need for limb development?

Answer 16

retinoic acid(via hensens node of primitive streak) and hox genes

Question 17

sonic hedgehog (shh)

Answer 17

binding growth factor binding to Patched, seen in A-P. Located in posterior dorsal mesenchyme. also seen in notochord for ventralization of neural tube.

Question 18

location of the zone of polarizing activity

Answer 18

posterior dorsal mesenchyme of limb bud

Question 19

How does SHH work?

Answer 19

SHH allows GLi to activate gene transcription by binding to patched receptor, turning on pattern formation

Question 20

WNT7A and BMPs

Answer 20

dorsal ventral axis org.

Question 21

What induces early limb bud?

Answer 21

FGF10 via lateral plate mesoderm. induces FGF8 to keep inducing FGF10

Question 22

what induces FGF4?

Answer 22

SHH, which then FGF4 induces SHH more

Question 23

Shh inhibits

Answer 23

BMP so FGF4/8 increases.

Question 24

Alx4

Answer 24

anterior mesoderm

Question 25

Progress zone

Answer 25

allows for more distal identity longer it stays there. Indicates specialization of tiem in each area for specialization of limb dev.

Question 26

what happens at week 6?

Answer 26

limbs rotate in parasag rotaion to rotate after limb formation.

Question 27

Location of apical ectodermal ridge

Answer 27

at distal end of lib bud ectoderm. without it you have no growth and no distal limbs and potentially no signalling of mesoderm.

Question 28

Hox8

Answer 28

posterior

Question 29

what induces SHH?

Answer 29

FGF 8

Question 30