Ganglion cells are the cells comprising masses of nerve tissues in the body. These masses are known as ganglia. The cells themselves consist of axon and dendrite structures that send and receive nerve impulses. The two most common types of ganglion cells are found within the adrenal glands and within the eye’s retina, although cells can also be found in other parts of the nervous system. These cells help transmit information throughout the body.
The adrenal gland’s cells are found specifically in the adrenal medulla, a portion of the gland that distributes the hormones norepinephrine and epinephrine into the bloodstream. These hormones direct the body when it is active or under stress, increasing heart rate, raising blood pressure, and so forth. These cells aid in these hormones’ release, so they play an important role in the body’s system of "fight or flight."
A retinal ganglion cell comprises the other main category of these cells. These cells serve as the mediator between the eye and the brain. Retinal cells collect information from the eye’s rods and cones and transmit this information to different regions of the brain via optical nerves. Various types of retinal cells address differing kinds of information, such as the amount of color and contrast in images. Types include midget cells, parasol cells, bistratified cells, and photosensitive cells.
Ganglion cells are also distributed throughout the parasympathetic and sympathetic nervous systems, areas that control the body in rest and in activity, respectively. Most parasympathetic cells, such as the adrenal cells, are located near organs, while sympathetic cells rest around the spinal cord. The parasympathetic cells function much the same as other ganglion cells in transmitting information throughout the body. In addition, the spinal ganglia relay information gained from the senses to the brain through sensory neurons. Clusters of ganglia called a plexus often work together to perform functions.
Although these cells are usually found in the peripheral nervous system outside the brain and spinal cord, some of these neurons are located inside the brain. Basal cells share connections with the brain stem, the thalamus and the cerebral cortex. As such, the cells play an important part in nearly every brain function from learning to body movement.
Ganglion cells populate the human body by the millions. These tiny neurons have been the source of numerous Nobel Prize studies. In the body, they are the conductors and the cornerstones of the nervous system.