Neurohistology Flashcards
what proteins allows discrimination between axons and dendrites
βIV spectrin - skeletal protein found in axons (+ some non-neuronal cells)
MAP2 - neuron specific cytoskeletal proteins found in dendrites
what is golgi stain
treating nervous tissue with potassium dichromate and silver nitrate results in silver precipitation (from silver chromate) in side the neurons
where are the cell bodies of multipolar motor neurons found
the ventral horn
Nissl substance is largely absent in the ______
axon
what is nissl substance
granules in the cytoplasm that consist of aggregates of free polyribosomes and rough endoplasmic reticulum
(strongly stained by basic dyes and appear as basophilic clumps on light microscopy)
what type of neuron is in the dorsal root ganglion
(cell bodies of) pseudounipolar neurons
where are satellite cells found
spinal ganglia
where are purkinje cells found
cerebellum
which layers of the cerebral cortex have no neuronal cell bodies only projections
layers 1 (molecular layer) and 6 (multiform layer)
the cerebral cortex is divided into __________ each housing neurons whose ___________ is characteristic of the layer
6 layers whose morphology is characteristic
what type of neurons are found in layer 3 of the cerebral cortex
small pyrimidal neurons
what is the primary type of cell found in layer 5 of the cerebral cortex
large pyramidal neurons
which layer of the cerebral cortex are granule (stellate) neurons found
layer 4
individual ganglion cells are surrounded by a layer of _________
satellite glial cells
what are satellite cells
glial cells that cover the surface of neuron cell bodies in ganglia of the peripheral nervous system
what are the layers of the cerebellar cortex
Molecular layer, purkinje layer, granule layer
what are the layers of the cerebellar cortex
Molecular layer (outer) (single layer) Purkinje layer, Granule layer (outer)
what cells are found in the granular layer of the cerebral cortex
Granule neurons (+golgi cells)
what cells are found in the molecular layer of the cerebral cortex
basket cells and stellate cells
why/how are purkinje neurons easily distinguished in a microscopic view
they have pear-shaped cell bodies and a distinctive dendritic tree. the largest cell in the cerebellum.
what is the blood-brain barrier
a barrier around blood vessels and along CNS surface composed of endothelial cells joined by tight junctions. prevents diffusion of solutes (>500daltons MW) and fluid into the brain and spinal cord
what glial cell is the blood brain barrier dependent on
astrocytes (end-feet) (covering vessels, maintenance and regulation, signalling endothelial cells to form tight junctions)
what areas of the brain are NOT surrounded by a blood brain barrier
circumventricular organs - including the choroid plexus and pituitary gland
neurohypophysis, pineal gland, subfornical organ and lamina terminalis, involved in neuroendocrine signalling
what are the circumventricular organs
highly vascularized structures located around the third and fourth ventricles and characterized by the lack of a blood–brain barrier (BBB). Specialized areas are points of communication between the blood, the brain parenchyma, and the CSF
what does myelin consist of
80% lipids 20% protein
what are the specific transporters at the endothelial cells part of the BBB
Energy-dependent ABC transporters: excrete xenobiotics (impermeability to drugs, antibiotics, etc) (remove toxic molecules from the brain
Amino acid transporters (L1) – in both membranes
GLUT1 glucose transporters
Ion exchangers
what are the specific transporters in the astrocyte end feet of the BBB
Glucose transporters: uptake and distribution to neurons. High metabolic activity.
K+ channels (Kir4.1)
Water channels (aquaporin-4) – critical function of astrocytes to bring water into the brain.
what are the differences between brain and peripheral capillaries
Brain capillary: no fenestrations, coated with astrocyte end-feet
Peripheral capillary: has fenestrations, associated with parenchyma cell, has lots of pinocytotic vesicles
what are pericytes?
vascular mural cells embedded in the basement membrane of blood microvessels
where are CNS pericytes located and what do they do
in the neurovascular unit between endothelial cells, astrocytes and neurons
they are important for blood vessel formation, maintenance of the blood–brain barrier, regulation of immune cell entry to the central nervous system (CNS), and control of brain blood flow.
what creates the selective permeability in the blood brain barrier
every solute that crosses the BBB must pass though the endothelial cells: allowing selective permeability to essential nutrients, to metabolise and leave
