AP patterning and organogenesis

Question 1

somites

Answer 1

transient blocks of tissue, and eventually give rise to the bone and cartilage of the trunk, to the skeletal muscles and to the dermis of the skin.

Question 2

Paraxial mesoderm

Answer 2

ventral-lateral mesoderm, on each side of the notochord.

Question 3

Pre-somitic mesoderm

Answer 3

between most recently formed somites and the node; the length of the pre-somatic mesoderm remains more or less constant.

Question 4

Signalling pathways involved in somite formation

Answer 4

• Wnt, Nodal and BMP
• Fibroblast growth factor (FGF)
• Retinoic Acid (RA)

Question 5

Vertebrae: somite-derived structure. Patterning controlled by Hox gene expression?

Answer 5

• Cervical = neck
• Thoracic = mid back
• Lumbar = lower back
• Sacral = sacrum (heiligbeen)
• Caudal = tailbone

Question 6

Gene expression pattern of Hoxa3 and Hoxd3 during AP patterning are
similar: both expressed in the….

Answer 6

vertebrae, neural tube, branchial arches and paraxial mesoderm.

Question 7

hox genes are located in …., targetted by ….. signalling

Answer 7

nucleus, Retinoic Acid (RA)