The neural tube forms from the folding of the neural plate during primary and secondary neurulation. This separates the surface ectoderm from the epidermis and forms the brain vesicles. Patterning of the neural tube occurs through gradients of proteins like TGF-Beta and Sonic Hedgehog. The brain expands through fluid secretion in the vesicles. Neurons are organized into layers and clusters in the brain and spinal cord. The epidermis develops from the surface ectoderm and includes structures like hair follicles, sweat glands, and layers like the stratum basale and stratum spinosum.