L8: Path of the Nervous System (Farina) Flashcards
encephalo-
prefix for brain
myelo-
prefix for white matter
polio-
prefix for grey matter
Nissl substance
cytoplasmic basophilic granular material (rER and polysomes)
myelin made by:
Schwann cells in the periphery, oligodendrocytes in the CNS
dura mater = outermost layer of meninges (periosteum outermost later in brain)
:)
pia mater is vascular and lies next to spinal cord/white matter
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ependymal cells
line ventricles
choroid plexus
- within ventricles
- produces CSF
- papillary-like structure
oligodendrocytes
-form myelin that wraps around axons in the CNS (same as Schwann cells in the PNS)**
3 types of glial cells
non-neuronal epithelial cells that line CNS
oligodendrocytes
astrocytes
microglia
astrocytes
- type of glial cell
- star-shaped cells w/ special stains (ie. GFAP immunostain)
- have elaborate cell processes that form the BBB**
- secrete paracrines that promote tight junction formation
microglia
- type of glial cell
- phagocytic cells
- have small nuclei with relatively little cytoplasm
Gitter cells
- phagocytic cells of the nervous system
- derived from microglia or monocytes
neuronophagia
phagocytes (microglia) gather around a necrotic neuron and phagocytose it to remove the debris
-char. of viral infections
Wallerian degeneration
focal damage to a myelinated axon results in degeneration of the axon segment distal to the site of damage
-Swiss cheese appearance
Wobblers
axonal damage from narrowing of spinal cord
spheroids
focal axonal swellings filled with degenerate organelles
liquefactive necrosis seen with ischemic injury in the CNS (ie. infarct)
:)
Astrocytosis
- increase in size and number of astrocytes in response to injury
- repair after CNS injury is largely the job of astrocytes (take role of fibroblasts in the brain)
- occurs in Alzheimer’s
gemistocytic astrocytes
plump, reactive astrocytes w/ eosinophilic cytoplasm
3 types hydrocephalus
1) Internal: fluid in ventricles
2) External: fluid in arachnoid space
3) communicating: fluid in ventricles and arachnoid space
* brachiocephalics prone*
* can be acquired*
microencephaly
abnormally small brain
hydranencephaly
near complete or complete absence of the cerebral hemispheres, leaving fluid-filled sacs by the meninges filled with CSF
porencephaly
cystic cavitation of the brain, usually involving cerebral white matter
lissencephaly
brain lacks normal gyri and sulci
-normal in rodents, non-mammals
dysraphia (neural tube closure defects)
anencephaly: absence of brain
prosencephalic hypoplasia: absence of the cerebral hemispheres w/ preservation of the brainstem
cranium bifidum/spina bifida: dorsal midline defect through which the brain/spinal cord and meninges can protrude
meningocele
herniation of meninges
meningoencephalocele
herniation of meninges and brain/spinal cord
viral causes of malformations
BVD feline panleukopenia hog cholera canine parvo border disease
veratrum californicum ingestion –>
cyclopia
storage diseases
Accumulation of substances in cells
- usually due to defective catabolism
- usually a result of a defect in lysosomal enzymes**
- usually autosomal recessive, progressive, fatal
How are storage diseases named?
according to the substrate that has defective degradation
- Sphingolipidoses
- Glycoproteinoses
- Mucopolysaccharidoses
- Glycogenoses
- Ceroid lipofuscinoses
Sphingolipidoses has defective degradation of what substrate?
molecules that form cell membranes
Glycoproteinoses has defective degradation of what substrate?
carbohydrate component of N-linked glycoproteins
Mucopolysaccharidoses has defective degradation of what substrate?
glycosaminoglycans
Glycogenoses has defective degradation of what substrate?
glycogen
Ceroid lipoguscinoses has defective degradation of what substrate?
lipofuscin
-“wear and tear” pigment which accumulates in old age
what most sensitive to ischemia?
- neurons and oligodendroglia
- grey matter more sensitive than white matter
- vascular occlusive lesions rare in domestic animals
neonatal maladjustment syndrome of foals
- “dummy foals”
- presumed to be due to ischemia and reperfusion
- lesions: laminar neuronal necrosis, multifocal small hemorrhages
malacia
necrosis of the CNS
Polioencephalomalacia
- sometimes assoc. with a high sulfur** intake
- a def. in thiamine or disturbance in thiamine metabolism also implicated
- occasionally observed in cases of water deprivation
- ruminants
thiamine deficiency
- required for carnivores
- seen in fox, cat, mink consuming fish or horse consuming plants containing a thiaminase
- CS: ataxia, neck ventroflexion, incoordination, mydriasis, convulsions
- Lesions: hemorrhage, necrosis and neuropil vacuolation in periventricular grey matter
CS of DIRECT salt poisoning (ingestion of excessive salt)
- mainly affects cattle
- v/d, paresis, blindness, abdominal pain
- congestion of abomasal mucosa, dark watery intestinal contents, NO CNS lesions
CS/lesions of INDIRECT salt poisoning (ingestion of high salt diet + restrictred water intake for several days)
- blindness, deafness, head pressing, convulsions
- lesions: cerebral edema, laminar cortical necrosis, nonsuppurative and eosinophilic meningoencephalitis
Nigropallidal encephalomalacia in horses
- due to ingestion of yellow star thistle and Russian knapweed
- putative neurotoxin causes glutathione depletion
- malacia in the globus pallidus and substantia nigra**
Leukoencephalomalacia in horses
- caused by moldy corn consumption for at least 1 mo.
- toxin = fumonisin
- CS: circling, visual impairment, weakness, pharyngeal paralysis, death
- lesion: necrosis of the cerebral white matter
Lead poisoning
- most common in cattle
- CS: staggering, m. tremor, convulsion, head pressing, blindness, hypersalivation, ruminal atony, recumbency, hyperesthesia, death
- lesions in cattle: only seen if dz course is at least several days; laminar cerebral cortical necrosis
- lesions in dogs: white matter edema in brain/spinal cord, demyelination
Malacic diseases (causing necrosis of CNS)
Polioencephalomalacia Thiamine def. Salt poisoning Nigropallidal encephalomalacia Leukoencephalomalacia Lead poisoning
malformations of the CNS
hydrocephalus Microencephaly Hydranencephaly Porencephaly Lissencephaly Disraphia Prosencephalic hypoplasia Cranium bifidum and meningoencephalocele Spina bifida
Ischemic lesions
infarct
neonatal maladjustment syndrome of foals
