Neuropathology Study Questions Flashcards
What is the function of oligodendrocytes?
Astrocytes?
Microglia?
Gitter cells?
Oligodendrocytes: form the myelin that wraps around axons in CNS.
Astrocytes: star shaped cells that form the blood-brain barrier; interstitial cells of the brain; possibly signal the endothelial cells to make tight junctions for blood-brain barrier
Microglia: phagocytic cells with small nuclei and little cytoplasm. Fixed macrophages of CNS.
Gitter cells: microglia ingesting myelin debris with foamy cytoplasm
What is central chromatolysis?
Degenerative change → first step to neuronal necrosis
Swelling of the cell, nucleus gets pushed off to the side, dispersal of Nissl substance
What is neuronophagia?
Microglia gather around a necrotic neuron and phagocytose it to remove the debris
Seen with viral infections
What are histologic characteristics of axonal degeneration?
Wallerian degeneration: focal damage to a myelinated axon resulting in degeneration of the axon segment distal to the site of damage
Axon degenerates (spheroid) → gitter cells remove axon and myelin debris → empty dilated axon sheath
What is a spheroid?
Focal axonal swellings filled with degenerate organelles
What kind of necrosis is typically seen in the CNS, and what are the characteristics of this type of necrosis?
Neuronal necrosis
“Red is dead,” shrunken, angular, pink cytoplasm indicates a dead neuron
Liquefactive necrosis
Can also have a pyknotic nucleus
What is astrocytosis?
Increase in size and number of astrocytes in response to injury; repair
Swell & divide as cell processes proliferate
What are gemistocytic astrocytes?
Plump, reactive astrocytes with eosinophilic cytoplasm; almost look like a dead neuron
Seen w/ significant damage
What is the appearance of Alzheimer’s type II astrocytes, and what disease process are these cells typically seen in?
Enlarged, vesicular nuclei that tend to cluster around the neurons
Seen w/ hepatic encephalopathy
What is hydrocephalus?
What are the different types of hydrocephalus?
In which breeds of dog is hydrocephalus most common?
Excess fluid in the brain
3 types:
Internal – fluid in ventricles
External – fluid in arachnoid space (rare)
Communicating – fluid in ventricles & arachnoid space (rare)
Most common in brachycephalic dogs and toy breeds
Define microencephaly
Abnormally small brain
Usually the cerebrum is the most affected part; can have smaller cranial cavity
Seen w/ BVD in cattle, classical swine fever in pigs
Define hydranencephaly
Cerebral hemispheres are almost gone or completely gone, leaving fluid-filled sacs formed by the meninges filled with CSF
Associated w/ viral infections → during development, they cause subventricular necrosis
Define proencephaly
Cystic cavitation of the brain, usually involving cerebral white matter
Less severe end of the spectrum as hydranencephaly & is caused by the same things
Define lissencephaly
Brain lacks normal gyri and sulci
Lhasa Apso’s = poster child
Can be normal in some species of mammals, but not normal in any of our domestic mammals (everything that is not a mammal is normally lissencephalic)
Define anencephaly
Absence of the brain = RARE