Nerve tissue is a complex organization of neurons, glial cells, vasculature, and connective tissue coverings. Neurons are specialized to conduct impulses in response to stimuli or environmental signals. To carry out this function, neurons have distinctive morphologies (as seen in the striking images below), possessing long cytoplasmic extensions (axons and dendrites), which allow them to form hundreds of connections with other neurons and cell types. Neurons are supported by glial cells, which are involved in nutrition, protection, and the formation of insulating sheaths.

Nerve tissue forms a complex, interconnected communication system throughout the body and is generally organized into two major divisions: the central nervous system (CNS, includes the brain and spinal cord) and peripheral nervous system (PNS, includes cranial, spinal, and peripheral nerves and ganglia located outside of the CNS). The PNS and CNS work together to receive, interpret, and integrate information in order to regulate a diverse range of essential physiological (e.g. respiration and blood pressure) and behavioral (e.g. defense and feeding) processes.

The purpose of this unit is to familiarize you with the histological features and functions of nerve tissue. It is not necessary for you to identify distinct functional regions within the central nervous system. The structures of the CNS will be covered in detail in the Neuroscience and Behavior course next semester.

The learning objectives for this unit are:

• Identify neurons and distinguish them from glial cells (astrocytes, oligodendrocytes, and ependymal cells) in sections of spinal cord and brain using light microscopy.
• Recognize neuronal cell bodies and satellite cells in sections of ganglia, and explain their functions.
• Identify Schwann cells, nodes of Ranvier, fibroblasts, and connective tissue layers in sections of peripheral nerves.

Slides and Micrographs