Systems Pathology: Central Nervous System PDF

Systems Pathology Central Nervous System Chapter 23 Lecture Outline I. Central Nervous System A. General Information 1. Basic CNS constituents a. Divisions of the CNS i. Brain & Spinal cord b. Histology of the C...

Systems Pathology Central Nervous System Chapter 23 Lecture Outline I. Central Nervous System A. General Information 1. Basic CNS constituents a. Divisions of the CNS i. Brain & Spinal cord b. Histology of the CNS Neurons Functional (parenchymal) cells of the nervous system Non-mitotic(permanent); no replacement when cell body injured No neoplasms of mature neurons Injury may produce: -Chromatolysis, Pyknosis -Wallerian degeneration (remember Neurilemmal sheath) -Neuronophagy -Inclusion bodies: Cytoplasmic vs. Intranuclear Death of neurons produces liquefactive necrosis, and in the late stages there is formation of a fluid-filled cyst. Neuroglial cells i. Astrocytes Most numerous of the cells of the central nervous system Major supporting cells in the brain, responsible for formation of the blood-brain barrier. After injury, these proliferate to create a reactive gliosis, the equivalent of fibrous scar formation elsewhere in the body. These are the most common cause of primary neoplasms of the CNS. ii. Oligodendrocytes These cells are the cells responsible for myelination in the CNS. Damage to these cells is seen in demyelinating diseases and also in the leukodystrophies. iii. Ependymal cells Single layer of cells that line the ventricles of the brain and the central canal of the spinal cord. Cilia on the surface of these cells help to keep CSF circulating. In selected areas of these cells there are masses of specialized capillaries derived from the pia mater called Choroid Plexus. These structures produce the plasma ultrafiltrate known as CSF. iv. Microglial cells (Mononuclear Phagocytic system) These are the phagocytes (neuronophagia) of the CNS. Have their origin as blood monocytes. In response to different types of insult these cells may aggregate to form microglial nodules, or they may take up lipid to form foamy macrophages known as Gitter cells. Systems Pathology, Lecture Notes © Dr. Perryman 38