Final answer:
Somites are mesodermal cell blocks that differentiate into sclerotomes, contributing to the vertebrae, ribs, and muscles of the back.
Step-by-step explanation:
In vertebrate embryonic development, somites are blocks of mesodermal cells located on either side of the neural tube. These somites further specialize into structures crucial for the formation of the back. A portion of each somite, called the sclerotome, differentiates into the vertebrae and ribs, which provide axial support to the body and contribute to the skeletal structure of the back. Additionally, somites give rise to the dermis of the dorsal skin and the segmental muscles that will become the skeletal muscles of the back. It is through a complex and tightly regulated process of gene expression that these somites form the connective tissues necessary for a functioning vertebrate skeleton.