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NEUROPATHOLOGY (CNS type cells (Microglial cells (Brain macrophage, Act as…
NEUROPATHOLOGY
CNS type cells
Neurons
Astrocytes
Forms BBB
Microglial cells
Brain macrophage
Act as Ag-presenting cells
Produce N2O, cytokines and chemokines
Oligodendrocytes
Create myelin sheath
Ependymal cells
Line ventricles and spinal canal
Choroid plexus epithelial cells
Produce CSF
Main responses of neurons to injury
Acute necrosis
Causes
Ischaemia
Hypoxia
Nutritional deficiency
Hypoglycaemia
Toxins
Trauma
Laminar cortical necrosis
acute necrosis that occurs in a selective pattern
Destruction of neurons in the deeper layers of the cerebral cortex
Occurs in
Thiamine deficiency and/or sulphur toxicity in ruminants
Salt poisoning/ water deprivation in swine and ruminants
Lead poisoning in cattle
Gross pathology
Oedema, herniation
Thin, white glistening line along middle of the cortex
Fluoresces under UV light in ruminants
Cortex ultimately becomes necrotic and collapses
Chromatolysis
Cell body swells and Nissl substance disperses to allow cell body to produce proteins for re-building
Occurs in grass sickness
Wallerian degeneration
Breakdown of an axon and its myelin sheath distal to the point of injury
Caused by
Axonal transection
Vascular
Inflammation
Compression
Crushing
Stretching
Toxins
Sequelae
Neuroma
Vacuolation
Hallmark of transmissible spongiform encephalopathies
Can also be artifact of fixation, caused by toxicoses and sometimes normal
Response of glial cells to injury
Oligodendrocytes
Degeneration
Demyelination
Astrocytes
Astrogliosis
Hypertrophy
Formation of glial fibres (scar tissue)
Astrocytosis
Hyperplasia
Microglia
Hypertrophy
Hyperplasia
Other responses to injury
Oedema
Vasogenic
Vascular injury and BBB breakdown
Extracellular accumulation of fluid
White matter
Hydrostatic
Increase hydrostatic pressure
Extracellular accumulation of fluid
periventricular
Cytotoxic
Altered cell metabolism
Ischaemia and hydropic degeneration
Intracellular accumulation of fluid
Consequences
Herniation
Foramen magnum
Compression of medulla oblongata
Death
Myelination disorders
Primary
Myelin sheath selective affected
Axon intact
Example
Canine Distemper
CAEV
Secondary
Loss of myelin following axon damage
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Vascular disturbances
Consequences
Depends on
Degree and duration
Size and type of vessel involved
Susceptibility of tissue to hypoxia
Acute neruonal necrosis
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Infarct
Causes
Thrombosis
Sepsis
DIC
Embolism
Fibrocartilaginous embolic myelopathy
Vasculitis
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Malacia
Softening of brain/spinal cord
results from necrosis
Pattern and location
Symmetrical
Metabolic
Nutritional
Genetic
Toxic
Assymetrical
Infectious
Vascular
Traumatic
Vasogenic Oedema
