18: CNS Histology

Question 1

Nissl bodies

Answer 1

Ribosomes in neuron soma actively synthesizing proteins

Question 2

Where do dendrites vs axons extend from in neurons?

Answer 2

Dendrite: from perikaryon
Axon: from axon hillock

Question 3

Are dendritic spines plastic?

Answer 3

Yes

Question 4

Neuropil

Answer 4

Dense network of nerve fibers, branches, synapses, and glial processes

Question 5

Presynaptic terminal bouton

Answer 5

Contains mito and synaptic vesicles, where nt is released from

Question 6

Typical size of synaptic cleft

Answer 6

20-30 nm

Question 7

Electrical synapse

Answer 7

Direct passive flow of electrical current between neurons, connected by gap junctions (connexons)

Question 8

Villi structure

Answer 8

Branching system of blood vessels running in fronds; fibrous core covered by cuboidal/columnar ep

Question 9

Two main layers of cerebral cortex

Answer 9

1. Archicortex (3 layers)

2. Neocortex (6 layers)

Question 10

What proportion of the cerebral cortex is neocortex?

Answer 10

90%

Question 11

Six layers of he neocortex

Answer 11

1. Molecular
2. External granular
3. External pyramidal
4. Inner granular
5. Ganglionic
6. Multiform (polymorphic)

Question 12

Molecular layer of neocortex

Answer 12

Most fibers and neuroglia

Question 13

Ganglionic layer of neocortex

Answer 13

Large pyramidal cells (Betz cells), especially in motor areas

Question 14

Multiform layer of neocortex

Answer 14

Diverse shapes of cells

Question 15

S/S Alzheimers

Answer 15

Memory failure, progressing steadily to involve motor skills, speech, and sensation

Question 16

What happens to gyri in Alzheimer’s

Answer 16

Thinning of gyri, particularly in frontal and temporal lobes

Question 17

What is seen on histo of Alzheimer’s

Answer 17

Amyloid B plaques, neurofibrillary tangles, neuronal loss

Question 18

Amyloid beta plaque histo

Answer 18

Amorphous, pink masses in cortex

Question 19

Neurofibrillary tangle histo

Answer 19

Flame-shaped skeins, abnormal accumulation of tau proteins

Question 20

Substantia nigra

Answer 20

Gray matter mass containing multipolar neurons with melanin

Question 21

Substantia nigra role

Answer 21

Fine motor function

Question 22

Neuromelanin

Answer 22

Granules in neurons, contain dopamine

Question 23

Parkinson’s disease

Answer 23

Degradation of substantia nigra, leading to loss of dopamine

Question 24

Etiology of Alzheimer’s and Parkinson’s

Answer 24

Unknown

Question 25

S/S Parkinson’s

Answer 25

Tremor, slow movement, rigidity

Question 26

Lewy bodies

Answer 26

Inclusions in remaining neurons of substantia nigra in Parkinson’s

Question 27

Lewy body composition

Answer 27

Alpha-synuclein aggregates

Question 28

Lewy body histo

Answer 28

Round, pink-staining inclusions with a pale halo

Question 29

Three layers of cerebellar cortex

Answer 29

1. Molecular layer
2. Purkinje cells
3. Granular layer

Question 30

Molecular layer of cerebellar cortex

Answer 30

Neuropil, scattered neuronal cell bodies

Question 31

Purkinje cell layer of cerebellar cortex

Answer 31

Dendrites extend thru to molecular layer, branching basket of nerve fibers

Question 32

Granular layer of cerebellar cortex

Answer 32

Various small, densely packed neurons + little neuropil

Question 33

Folia

Answer 33

Organization of cerebellar cortex

Question 34

Gray matter of SC

Answer 34

Central mass, shape of butterfly

Question 35

Parts of gray matter of SC

Answer 35

Ventral, dorsal, and lateral horns + central canal

Question 36

White matter of SC

Answer 36

Ascending (sensory) + descending (motor) tracts

Question 37

Three layers of CT around nerves and what they surround

Answer 37

Endoneurium: around neurolemmocytes
Perineurium: around fascicles of axons
Epineurium: around peripheral nerve

Question 38

What is the epineurium continuous with?

Answer 38

Spinal meninges