Histology of the CNS

Question 1

how would you identify a neuron on a histological slide?

Answer 1

it has a cell body with a large nucleus with a well-developed nucleolus, and Nissl substance/bodies

Question 2

What does it mean when it is said that dendritic spines are plastic?

Answer 2

they can either appear or regress if they are not being used

Question 3

Where does the axon of a neuron appear from the cell body from?

Answer 3

the axon hillock

Question 4

What does neuropil act as?

Answer 4

connective tissue for the neuron

Question 5

What are the neurites that receive information and transmit it to the cell body are called what?

Answer 5

dendrites

Question 6

the granular material that is present in the entire cell body and proximal part of the dendrites?

Answer 6

Nissl substance/ nissl bodies

Question 7

Small projections that extend from the branches of the dendrites?

Answer 7

dendritic spines

Question 8

What is the purpose of the dendritic spines?

Answer 8

they increase the receptive area

Question 9

Where does the action potential originate at?

Answer 9

the axon hillock

Question 10

What does the presynaptic terminal bouton contain?

Answer 10

mitochondria and synaptic vesicles containing NTs

Question 11

what separates the pre- and post-synaptic membranes?

Answer 11

The synaptic cleft

Question 12

What does the post synaptic cell membrane contain?

Answer 12

receptors for the NT and ion channels to initiate a new impulse

Question 13

a synapse in which the postsynaptic membrane is on a dendrite of another neuron is called what?

Answer 13

axodendritic synapse

Question 14

a synapse in which the postsynaptic membrane is on the cell body (soma) of another neuron is called what?

Answer 14

axosomatic synapse

Question 15

A synapse in which the postsynaptic membrane is on the axon of another neuron is called what?

Answer 15

axoaxonic synapse

Question 16

Where do electrical synapses occur?

Answer 16

at gap junctions

Question 17

What do gap junctions contain that link pre- and post-synaptic membranes?

Answer 17

they contain connexon proteins

Question 18

What are the supporting cells in the CNS called?

Answer 18

Glial cells

Question 19

What are the proximal regions of astrocytes reinforced with?

Answer 19

intermediate filaments made of glial fibrillary acid protein (GFAP)

Question 20

What is the hallmark marker for identifying astrocytes?

Answer 20

the glial fibrillary acid protein (GFAP)

Question 21

What is the role of astrocytes?

Answer 21

support the neurons, establish the BBB, can remove NTs from the synaptic cleft

Question 22

when astrocytes extend their processes and contact another structure what do they establish?

Answer 22

foot pads known as perivascular feet or perineural feet

Question 23

what is the role of perineural feet?

Answer 23

helps astrocytes reuptake NTs

Question 24

what is the role of the perivascular feet?

Answer 24

they block the pores that are found within the capillary beds that feed into the nervous system–> BBB

Question 25

where are ependymal cells found?

Answer 25

lining the brain ventricles and central canal of the spinal cord

Question 26

what type of cells are ependymal cells?

Answer 26

columnar or cuboidal cells

Question 27

What is the role of ependymal cells?

Answer 27

facilitate the movement of CSF and likely involved in absorption

Question 28

Where is the choroid plexus found?

Answer 28

in the roofs of the 3rd and 4th ventricle and parts of the lateral ventricular walls

Question 29

What is the choroid plexus?

Answer 29

thin, well-vascularized pia mater covered by cuboidal ependymal cells

Question 30

what contributes to the blood-CSF barrier?

Answer 30

tight junctions (zonula occludens) between epithelial cells

Question 31

what is the role of microglia?

Answer 31

remove damaged or inactive synapses or other fibrous components; major mechanism of immune defense in the CNS

Question 32

What do microglia originate from?

Answer 32

monocytes

Question 33

what should you look for when trying to identify microglia histologically?

Answer 33

a simple elongated nuclei

Question 34

What is the role of oligodendrocytes?

Answer 34

they extend processes that enwrap nearby axons in myelin

Question 35

what do you look for when looking for oligodendrocytes histologically?

Answer 35

a very round and almost perfectly circular nuclei

Question 36

What are the glial cells in the PNS?

Answer 36

neurolemmocytes (schwann cells) and satellite cells

Question 37

What are neurolemmocytes and satellite cells derived from?

Answer 37

NCCs

Question 38

What are the functions of neurolemmocytes?

Answer 38

myelinate peripheral nerves- providing electrical insulation

Question 39

what are the functions of satellite cells?

Answer 39

provide structural and metabolic support for neuronal cell bodies

Question 40

where are satellite cells found?

Answer 40

in dorsal root ganglions (DRG)

Question 41

What is the outermost layer of the cerebral cortex?

Answer 41

the molecular layer

Question 42

what is found in the molecular layer?

Answer 42

fibers and neuroglial cells

Question 43

what is the 2nd layer of the cerebral cortex?

Answer 43

external granular later

Question 44

what is the 3rd layer of the cerebral cortex?

Answer 44

external pyramidal layer

Question 45

what is the 4th layer of the cerebral cortex?

Answer 45

inner granular layer

Question 46

what is the 5th layer of the cerebral cortex?

Answer 46

ganglionic layer

Question 47

what is found in the ganglionic layer?

Answer 47

extra-large pyramidal cells (Betz cells)

Question 48

what is the 6th layer of the cerebral cortex?

Answer 48

multiform (polymorphic) layer

Question 49

What is a clinical sign of alzheimer's disease?

Answer 49

thinning of gyri- particularly those of the frontal and temporal lobes

Question 50

what is identifiable histologically if a patient has alzheimer's disease?

Answer 50

amyloid (amyloid B) plaques and neurofibullary tangles (tau protein)

Question 51

what is the substantia nigra important for?

Answer 51

fine control of motor function

Question 52

what do neurons in the substantia nigra contain?

Answer 52

numerous membrane bound granules of neuromelanin pigment

Question 53

What does neuromelanin contain?

Answer 53

dopamine

Question 54

what is the role of dopamine?

Answer 54

it has inhibitory effects in the brain in areas dedicated to movement

Question 55

what are the distinctive inclusions seen in the remaining neurons in the substantia nigra called?

Answer 55

Lewy bodies

Question 56

What are lewy bodies composed of?

Answer 56

aggregates of the protein alpha-synuclein and other proteins

Question 57

How many layers make up the cerebellar cortex?

Answer 57

3

Question 58

What is the first/ most superficial layer of the cerebellar cortex?

Answer 58

the molecular layer

Question 59

what is located in the molecular layer of the cerebellar cortex?

Answer 59

neuropil and scattered neuronal cell bodies (basket cells)

Question 60

what is the second layer of the cerebellar cortex?

Answer 60

purkinje cells

Question 61

What is the third layer/ deepest layer of the cerebellar cortex?

Answer 61

granular layer

Question 62

what is located deepest in the cerebellar cortex?

Answer 62

the cerebellar medulla

Question 63

where does the central canal of the spinal cord lie?

Answer 63

in the central commissure of the gray matter

Question 64

what is found immediately around the neurolemmocytes and consists of reticular fibers, fibroblasts, and capillaries?

Answer 64

endoneurium

Question 65

what enwraps the fasicles of axons, neurolemmocytes, and endoneurium?

Answer 65

perineurium

Question 66

what is a dense irregular fibrous coat in between fasicles and surrounding the peripheral nerve?

Answer 66

epinerium

Question 67

what are neurofibrillary tangles formed by?

Answer 67

an abnormal accumulation of tau