Neurohistology

Question 1

what proteins allows discrimination between axons and dendrites

Answer 1

βIV spectrin - skeletal protein found in axons (+ some non-neuronal cells)
MAP2 - neuron specific cytoskeletal proteins found in dendrites

Question 2

what is golgi stain

Answer 2

treating nervous tissue with potassium dichromate and silver nitrate results in silver precipitation (from silver chromate) in side the neurons

Question 3

where are the cell bodies of multipolar motor neurons found

Answer 3

the ventral horn

Question 4

Nissl substance is largely absent in the ______

Answer 4

axon

Question 5

what is nissl substance

Answer 5

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)

Question 6

what type of neuron is in the dorsal root ganglion

Answer 6

(cell bodies of) pseudounipolar neurons

Question 7

where are satellite cells found

Answer 7

spinal ganglia

Question 8

where are purkinje cells found

Answer 8

cerebellum

Question 9

which layers of the cerebral cortex have no neuronal cell bodies only projections

Answer 9

layers 1 (molecular layer) and 6 (multiform layer)

Question 10

the cerebral cortex is divided into __________ each housing neurons whose ___________ is characteristic of the layer

Answer 10

6 layers whose morphology is characteristic

Question 11

what type of neurons are found in layer 3 of the cerebral cortex

Answer 11

small pyrimidal neurons

Question 12

what is the primary type of cell found in layer 5 of the cerebral cortex

Answer 12

large pyramidal neurons

Question 13

which layer of the cerebral cortex are granule (stellate) neurons found

Answer 13

layer 4

Question 14

individual ganglion cells are surrounded by a layer of _________

Answer 14

satellite glial cells

Question 15

what are satellite cells

Answer 15

glial cells that cover the surface of neuron cell bodies in ganglia of the peripheral nervous system

Question 16

what are the layers of the cerebellar cortex

Answer 16

Molecular layer, purkinje layer, granule layer

Question 16

what are the layers of the cerebellar cortex

Answer 16

Molecular layer (outer)
(single layer) Purkinje layer, 
Granule layer (outer)

Question 17

what cells are found in the granular layer of the cerebral cortex

Answer 17

Granule neurons (+golgi cells)

Question 18

what cells are found in the molecular layer of the cerebral cortex

Answer 18

basket cells and stellate cells

Question 19

why/how are purkinje neurons easily distinguished in a microscopic view

Answer 19

they have pear-shaped cell bodies and a distinctive dendritic tree. the largest cell in the cerebellum.

Question 20

what is the blood-brain barrier

Answer 20

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

Question 21

what glial cell is the blood brain barrier dependent on

Answer 21

astrocytes (end-feet) (covering vessels, maintenance and regulation, signalling endothelial cells to form tight junctions)

Question 22

what areas of the brain are NOT surrounded by a blood brain barrier

Answer 22

circumventricular organs - including the choroid plexus and pituitary gland
neurohypophysis, pineal gland, subfornical organ and lamina terminalis, involved in neuroendocrine signalling

Question 23

what are the circumventricular organs

Answer 23

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

Question 24

what does myelin consist of

Answer 24

80% lipids 20% protein

Question 25

what are the specific transporters at the endothelial cells part of the BBB

Answer 25

 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

Question 26

what are the specific transporters in the astrocyte end feet of the BBB

Answer 26

 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.

Question 27

what are the differences between brain and peripheral capillaries

Answer 27

Brain capillary: no fenestrations, coated with astrocyte end-feet Peripheral capillary: has fenestrations, associated with parenchyma cell, has lots of pinocytotic vesicles

Question 28

what are pericytes?

Answer 28

vascular mural cells embedded in the basement membrane of blood microvessels

Question 29

where are CNS pericytes located and what do they do

Answer 29

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.

Question 30

what creates the selective permeability in the blood brain barrier

Answer 30

every solute that crosses the BBB must pass though the endothelial cells: allowing selective permeability to essential nutrients, to metabolise and leave