The cerebellum is organized as three layers: outer molecular layer, thin middle layer of Purkinje cells, and thick inner granular layer. The cerebellum functions to coordinate the activities of muscles within the body. Examine glial cells and other types of neurons in sections of the cerebellum (sample 1 and sample 2 and in the images below.

Identify:

• Neurons of the molecular layer (ML)
• Neurons of the granular layer (GL)
• Purkinje cells (P) (a type of neuron) between these layers

Examine these two sections of spinal cord (sample 1 and sample 2) and the images below. In contrast to the cerebrum and cerebellum, gray matter is internal to white matter in the spinal cord. Identify the central gray matter (G), containing motor neurons (interneurons) and abundant astrocytes, the central canal (C) lined by ependymal cells (E), and the outer white matter (W), consisting largely of myelinated axons (A) and oligodendrocytes (O). The myelin, composed mainly of lipid, is lost during tissue preparation, leaving clear circular spaces around the small eosinophilic axon when seen in cross section.

Clinical note: The CNS is subject to various diseases in which there is destruction of the myelin sheaths, such as multiple sclerosis (MS). The functions and body regions affected by MS depend on where in the CNS the focal areas of demyelination occur. Weakness and paralysis of one or more limbs are common sequelae of this disease.
 

Now for ganglia.