What is the difference between oligodendrocytes and Schwann cells? What structure do ependymal cells form? What substance do ependymal cells produce? What are microglial cells? What is the cerebrum responsible for? Through what structure of the skull does the spinal cord move through? What is the difference between the thalamus and the hypothalamus? What structures assist in regulating the endocrine system? What are the differences between the peripheral nervous system and the central nervous system? What is the difference between gray matter and white matter? What is efferent versus afferent?