Nerve Tissue Al-Maarefa College
Jan 18, 2016
Objective
• Understand the microscopic difference between excitable and non-excitable cells present in the nervous system.
Nerve Fiber (Axon)• Nerve fibers are long nerve cell processes (axon
cylinder, axon) with a surrounding membrane• Schwann cells (neurolemmocytes, peripheral glial
cells) enfold the axon and form an insulating cover known as Schwann’s sheath (neurolemma).
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Stain: osmium tetroxide; magnification: × 1000
Nerve Fiber (Axon)• Myelinated nerve fiber, i.e., the axon is covered by a
myelin sheath, which is rich in lipids.• Every 0.8 to 1.0 mm, a node of Ranvier subdivides
the myelin sheath into segments or internodes.
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Stain: osmium tetroxide; magnification: × 1000
Sciatic nerve – cross section• 1 Fascicle (nerve fiber bundle)• 2 Perineurium• 3 Epineurium• 4 Artery• 5 Vein• 6 Adipose
tissue
Stain: alum hematoxylin; magnification: × 10Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
Glial Cells
• Glial cells (Neuroglia) or (Glia)• (Greek "glue”• Non-neuronal cells that maintain homeostasis,
form myelin, and provide support and protection for the brain's neurons
• They occupy the entire space between neurons and separate nerve cells from blood vessels
Glial Cells - Functions
1. Surround neurons and hold them in place2. Supply nutrients and oxygen to neurons3. Insulate one neuron from another4. Destroy pathogens and remove dead neurons
Astrocytes
Kuehnel, Color Atlas of Cytology, Histology, and Microscopic Anatomy
• Most abundant• Deal wit homeostasis – relate to vessels
Microglia
• Oligodendrocytes:– Closely related to
neurons– Provide myelin
protection for CNS neurons