Final answer:
During stratification of the ectoderm, cells differentiate to form epidermal cells and the neural plate. Growth factors play a crucial role in signaling cells to differentiate appropriately, leading to the development of the nervous system, sensory organs, and epidermis.
Step-by-step explanation:
During the stratification of the ectoderm, a series of developmental processes occur within an embryo that underpin the formation of various tissues and organs. Gastrulation leads to the formation of three germ layers, one of which is the ectoderm. The ectoderm differentiates into two main pathways: one leads to the formation of epidermal cells at the edges due to signaling by growth factors, while the cells in the center form the neural plate, which will give rise to the nervous system. If signaling is disrupted, the ectoderm may not stratify properly, potentially leading to an entire ectodermal differentiation into neural tissue.
The mesoderm and endoderm also develop from these germ layers, resulting in the formation of additional cell types and organs. By the end of stratification, the ectoderm has formed tightly connected epithelial sheets that will become the central and peripheral nervous systems, sensory organs, epidermis, hair, and nails. Meanwhile, the mesodermal cells develop into the skeleton, muscles, connective tissue, heart, blood vessels, and kidneys, and the endoderm forms the epithelial lining of the gastrointestinal tract, liver, pancreas, and lungs.