Final answer:
The morphogen responsible for setting the anterior-posterior axis in developing limbs is C. Sonic hedgehog (Shh). This protein plays a critical role in limb patterning during embryogenesis.
Step-by-step explanation:
The morphogen primarily responsible for setting the anterior-posterior axis in the developing limb is C. Sonic hedgehog (Shh). Sonic hedgehog is a protein that is crucial in the regulation of embryonic development, and it is particularly important in limb development. This protein acts as a signaling molecule that communicates to embryonic cells their position relative to each other, effectively guiding the proper patterning of the limb along the anterior-posterior axis.
Understanding limb development is essential in developmental biology, which often investigates key events like axis formation and the role of specific morphogens. Axis formation is a fundamental concept, which also includes the dorsal-ventral and left-right axes. These axes are established during early embryogenesis and are influenced by the expression of various genes, including those in the Wnt and Hox gene families.