Question

You are studying developmental biology in invertebrates and you find that hedgehog, Dpp, and Dll are expressed in a particular cell. Based upon this you can assume that these cells will be involved in patterning and growth along which aspect?

1) the dorsal aspect
2) the ventral aspect
3) a proximal-distal aspect, as in head to tail
4) a proximal-distal aspect, as in limbs or mouth parts
5) none of the above

Answer 1

Cells expressing hedgehog, Dpp, and Dll will likely be involved in the development of limbs or mouth parts, indicating a role in proximal-distal patterning.

Step-by-step explanation:

When considering the expression of hedgehog, Dpp, and Dll in a particular cell, it is indicative that these cells will be involved in patterning and growth along a proximal-distal aspect, particularly in the context of limb development or mouth parts (option 4). This axis is related to the formation of structures extending from the main body of an organism, such as limbs or antennae.

During developmental stages, the limb bud elongates and cells begin to differentiate in a proximal-to-distal order, which is regulated by gene expression and signaling pathways that include the ones mentioned. The Spemann and Mangold experiment demonstrates the importance of dorsal cells in axis formation; however, the genes in question here (hedgehog, Dpp, and Dll) are more closely related to the development of extremities rather than the establishment of dorsal-ventral patterning.