Lect. 25 - Limb Devpt I Flashcards Preview

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Flashcards in Lect. 25 - Limb Devpt I Deck (18):
1

Result of experiment removing half of the limb

Remaining half will form a complete limb

2

Role of Tbx5 in initiation of limb development

Initiates future forelimb

3

Role of Tbx4 and Pitx-1 in limb development

Initiates future hindlimb

4

What are the initial initiators of limb development?

Tbx4 and Tbx5

5

Role of Gli3 and Hand2 in initiation of limb development

Gli3 (anterior) and Hand2 (posterior) fix AP axis

6

Role of FGF-10 in initiation of limb development

Mesoderm to ectoderm

7

Role of FGF-8 in initiation of limb development

Ectoderm to mesoderm

8

What are the 3 axes that define the vertebrate limb?

Dorsoventral; anterior-posterior axis; and proximodistal axis

9

Hox8

Determine position of ZPA via its highest concentration; expression is induced by RA

10

Shh

Signal produced by ZPA; also maintains structure and function of AER; induces expression of gremlin

11

Gremlin

Inhibits BMP-2 which inhibits FGF-4 in AER and inhibits Gli-3 in posterior part of limb bud

12

Gli-3

In anterior part of limb bud; inhibits expression of shh in anterior part of limb bud

13

Interactions of AER and limb bud mesoderm

Interacts w/ underlying limb bud mesoderm and promotes continued outgrowth of limb bud

14

Role of Hox genes in limb patterning

Pattern formation in the proximodistal limb axis

15

Relationship of Msx expression to the distal mesenchyme

Cells in the distal limb bud express Msx-1

16

What factors makes up the outgrowth-promoting signal?

FGFs (8, 4, 9, 17) and Wnts

17

What is the role of apoptosis in limb development?

It's a mechanism for morphogenesis; posterior necrotic zone (will become the axilla) and areas b/w future digits

18

Results of experiment dividing the disc into two halves and physically separating the 2 halves

Each half will form a normal limb