Neuro 1 Flashcards
Holoprosencephaly
• associated anomalies
• caused by
- Failure of forebrain to divide into cerebral hemispheres
- Associated with cyclopia and facial anomalies
** loss of midline structure
Cause:
- Ewe eats plant -Veratrum californicum on DAY 14
- must be other causes bc we see this sometimes
(in humans – Fetal alcoholism, Morning after pill)
Encephaloclasic defects (2 forms)
• what species mainly
• caused by
• mainly ruminants
continuum of dz
- Porencephaly -smaller
- Hydranencephaly -larger
always fetal dz
- *start as necrosis of parenchyma of the brain
- liquifactive necrosis of white matter –> partial to total loss of brain
Main causes:
- Viral – BVD, bluetongue
Ventricular dilation
How can you tell if it is congenital?
Accumulation of CSF in ventricular system Causes: - Obstruction of outflow - decreased absorption - Excess production
Can be congenital or acquired
-Congenital –> enlargement of calverium due to lack of closure!
Hydromyelia
Dilation of central canal of spinal cord
- -Congenital or acquired
- Still lined by ependymal cells
Syringomyelia
- Tubular cavitation in spinal cord
- May communicate with central canal, but NOT lined by ependymal cells
- Syringo- = Tube/fistula
Cerebellar hypoplasia
Link to viral destruction of external granular layer
- Feline panleukopenia
- BVD virus
• they like rapidly dividing cells
Dysraphism / Meningocele
Protrusion of meninges through defect in dorsal aspect of cranium or vertebral column
• covered just by skin or meninges
• sometimes brain/spinal cord can come thru with it
** Raph- = “seam”
Meningoencephalocele
brain + meninges protrude thru dorsal cranium
Meningomyelocele
spinal cord + meninges protrude thru dorsal cranium
Colonic aganglionosis
‘Overo lethal white foal syndrome’
• American Paint horse foals
= Unpigmented hair and skin
- 1 AA mutation in Endothelin receptor B gene
- -> lack signal of Neural crest stem cell
- -> into Lg intestinal ganglia & lack of Melanocytes
- -> mechonium stays in GI tract
- -> death from intestinal obstruction
Name the types of glial cells
- Macroglia
- astrocytes
- oligodendroglia - Ependymal cells /choroid plexus
- Microglia
- derived from Monocytes
Neuropil
term for Cellular Processes of neurons and glia that compose the GRAY matter of the brain/cord
Leptomeninges
Arachnoid membrane & pia mater + space btwn
-Ruminants often have Melanosis
Nissl substance
- the predominant cytoplasmic feature of most neuronal cell bodies
- granular/ smudged basophilic material
- RER & polysomes
**not in axons!
What do you call a “group of neuronal cell bodied in the CNS”?
What are axons called?
Nuclei
Tracts – named for sites of origin and termination
What do you call a “group of neuronal cell bodied in the PNS”?
What are axons called?
Ganglia
Nerves
- UMN axons = confined to the CNS
- extend to neurons in the brain stem and spinal cord - LMN extend from cell bodies in the brain stem or spinal cord into cranial nerves and spinal nerves of the PNS
Myelinating cells of PNS vs CNS
PNS = Schwann cells (some cells have Amphicytes)
CNS = oligodendrocytes
What does myelin internode refer to?
the area where the myelin is on an axon
–the space btwn these are called Node of Ranvier
What is Perineurium?
What is Epineurium?
Peri = the fibrous tissue that bundles axons into fascicles
Epi = contiguous with the dura mater, ensheaths the entire nerve
-contains ample adipose tissue
What is the main leukocyte observed in normal neuron?
Mast cell
Which axon is more likely to be myelinated?
> 2 OR <2 micron micron diameter
Axons that are Larger than 2 microns
Which enzymes are assoc’d with Anterograde transport?
Anterograde
- protein kinesin –Faster
- microtubule- associated protein dynamin –Slower
Retrograde
*dynein
where does sympathetic nerves (LMN) arise from?
– what can damage to these nerves cause?
- T1 to L4
- Horner’s syndrome
(ptosis, miosis, and enophthalmos)
where does parasympathetic nerves (LMN) arise from?
– what CNs do the become?
- CN 3 = to control pupils and eyelids
- CN7 = lacrimal glands
- CN 7 and 9 = salivary glands
- CN 10 = heart
- caudal segments = caudal viseara
Astrocytes
- 2 types
- function
- Protoplasmic = gray matter
- Fibrous = white matter
- structural support, neurotransmitter metabolism, maintenance of ionic balance, and transfer of metabolites from blood to neurons
What is the role of astrocytes in immature brain?
guide migrating neuronal cell bodies and developing axons
What is the glia limitans?
A network of astrocytic processes just beneath the pia mater
What histochemical process is used to ID astrocytes?
- Metallic stains
- IHC for glial fibrillary acidic protein (GFAP)
= major cytoskeletal elements
What is the importance of Microglia?
- derived from monocytes
- APC’s = innate immune system of the CNS
- least common glial cell in a normal brain
Ependymal cells
- line the ventricles of the brain and the central canal of the spinal cord.
- ciliated cells function in the flow of cerebrospinal fluid
Choroid plexus epithelium
- production of CSF
- maintenance of the blood-CSF barrier
- share a common derivation with ependymal cells
Where does a seizure localize the lesion to?
Prosencephalon
What are the steps of neurulation?
- Neural plate (formed from ectoderm)
- Neural groove (neuroectoderm)
- Neural tube closure
- Dehiscence
What is astrocytes role in injury?
- Take up edema fluid (swell)
- Hypertrophy –> ↑ processes & GFAP
- Proliferation
- Glial “scars” – around necrotic foci
What are Ependymal cells?
- lining ventricular system
- Ciliated –> move CSF
- Gap junx (Zonulae adherentes)
- Express Vimentin
What are choroid plexus epithelial cells?
- line ventricles
- Microvilli (few cilia)
- Secrete CSF
- Zona occludentes (CSF-Brain Barrier)
- Express Cytokeratin
What is the pachymeninges?
Dura Mater
What is the leptomeninges?
Arachnoid & Pia mater
What are the 1° vesicles of the neural tube?
What do they become?
- Pros-encephalon (forebrain)
–> Tel-encephalon
• lateral ventricles & cerebral cortex
–> Di-encephalon
• Thalamus /hypothalamus - Mes-encephalon (Midbrain)
- -> stays Mesencephalon
- Rhomb-encephalon (hindbrain)
–> Met-encephalon
• Pons /Cerebellum
–> Myel-encephalon
• Medulla oblongata
Prosenchephalic anomalies
- Prosencephalic hypoplasia
- Holoprosencephaly
- Encephaloclastic defects
• Porencephaly
• Hydranencephaly
