Important genes of embryogenesis

Question 1

Sonic hedgehog gene (Shh)

Answer 1

Produced at base of limbs in zone of polarizing activity

Involved in patterning along
*anteroposterior axis and CNS development

mutation can cause *holoprosencephaly

Question 2

Wnt-7 gene

Answer 2

Produced at *apical ectodermal ridge (thickened ectoderm at distal end of each developing limb)

Necessary for proper organization along *dorsal-ventral axis

Question 3

FGF gene

Answer 3

Produced at *apical ectodermal ridge

Stimulates mitosis of underlying mesoderm, providing for *lengthening of limbs.

FGF R3 mutation caused *achondroplasia

Question 4

Homeobox (Hox) genes

Answer 4

Involved in segmental organization of embryo in a *craniocaudal direction

Code for transcription
factors

Hox mutations Žcauses appendages in wrong locations