SBPMD Histology Laboratory ManualNerveLearning objectives:
The central nervous system (CNS) comprises: (1) nerve cells (neuronal cell bodies) and their dendrites and axons (both myelinated and unmyelinated), (2) supporting cells, the neuroglia (oligodendroglia, astrocytes and microglia), (3) the pia and arachnoid, (4), and (5) blood vessels. The peripheral nervous system (PNS) contains: (1) neurons (organized into clusters called ganglia), (2) supporting cells including satellite cells associated with the ganglionic neurons, (3) Schwann cells associated with axons and forming the myelin sheath, (4) connective tissue elements (endoneurium, perineurium and epineurium) and (5) blood vessels. The neuron is the structural and functional unit of the nervous system. Neurons are highly polarized cells. The cell body contains the nucleus and synthetic apparatus. The highly branched dendrites are the receptive pole and axons are the transmitting pole. Note: Axons are often referred to as nerve fibers. Each neuron contacts (synapses) on cell bodies, dendrites or axons of other neurons so that each neuron is a functional part of the interconnecting unit in the network of the entire nervous system. Neurons act as integrators, conductors and transmitters of coded information. Nervous tissue is characterized by its extreme specialization for irritability and conductivity. The supporting cells are in intimate contact with the neurons and their processes in both the CNS and the PNS. Actually the entire surface of many neurons, with few exceptions (synapses and nerve endings), is enveloped and "insulated" from other tissues by processes of supporting cells. These cells are interposed between each neuron (with a few exceptions) and the blood capillaries and adjacent neurons. The meninges (connective tissue elements) surround the central nervous system, capsules surround some sense organs and ganglia, and the endo-, peri-, and epineurium of peripheral nerves are also formed by connective tissue elements. Exchange of gases, nutrients, and metabolic products between the neurons and blood vessels takes place through these tissues. The microglia of the CNS and the histiocytes of the PNS are macrophages. The detailed structure and function of the nervous system will be studied during the neurosciences course. The following class slides and electron micrographs will serve to acquaint you with nervous tissue as one of the four basic tissues. Lab Activities
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