The nervous system is formed of specialized cells called neurons that use electrical and chemical signals to carry information to and away from the brain. Neurons contact each other, and other tissues, at a specialized region of the cell called a synapse. There, chemicals called neurotransmitters are released by one neuron and received by the other. Long, thin regions of the neuron that carry information from a distant location to the neuronal cell body are called axons and dendrites. Neurons connect to, or inner-vate, every type of tissue in the body, including bones, skin, organs, and muscles. The information they carry allows organisms to sense the world, think, react, and maintain body function. Normal growth and development of the nervous system is necessary for forming a normal organism.

Genetic Basis of Development

Many of the accepted...