Histology Chapter 12
Nerve Tissue Learning Objectives
Multipolar = 2 or more dendrites
Intercalated neurons = interneurons
1.
Which pathways commonly utilize bipolar neurons?

Bipolar neurons are rare and usually employed in the special senses
2.
What makes up the nissl bodies in the perikaryon of a neuron?
 Ribosomal content stains as Nissl bodies (one stack = 1 body)
3.

How can neural stem cells be identified?
Neural stem cells produce the protein nestin

What do Golgi type I and type II neurons do?
Type I = CNS motor; type II = CNS interneurons
4.
5.
Describe substancia nigra neurons in Parkinsonian patients:
 Gliosis (increase in # of glial cells)
 Lewy bodies in the neurons (accumulation of neurofilaments, α-synuclein, ubiquitin)
6.

What is a periaxoplasmic plauqe?
Periaxosomal plaques are sites in the axon terminal where protein synthesis occurs
7.
The active zones of buttons are rich in which vesicle docking proteins (3)?
 SNAREs
(vesicle docking and fusion, porocytosis)
 Synaptotagmin
(vesicle docking and fusion, porocytosis)
 Rab-GTPase docking complexes
8.
How does porocytosis differ from exocytosis?
 Porocytosis appears to involve smaller release rates and amounts of neurotransmitter
9.
How do cocaine and amphetamines influence the synaptic cleft, generally?
 High-affinity reuptake of catecholamines is slowed by cocaine
 Amphetamine prevents catecholamine storage
10. Which enzyme “inactivates” catecholamines? Which “destroyes” them?
 COMT (catechol O-methyltransferase) inactivates
 MAO destroys
11. Which motor protein carries material to the periphery? Retrograde transporter?
 Kinesin moves material to the presynapse
 Dynein is the retrograde transporter
12. What transcription factor is important for Schwann cell differentiation from neural crest?
 Sox-10, bitch
13. What transmembrane proteins are expressed to compact the myelin sheath?
 P0, PMP22, and MBP (protein 0, peripheral myelin protein 22 & myelin basic protein)
14.
What is inside the major dense lines of a TEM micrograph of a schwann cell? What are
intraperiod lines?
 Major dense lines contain cytoplasm and the positively charged portions of P0 and MBP
 Intraperiod lines are extracellular space (outer membrane leaflets)
15. What do you call the gap in the membrane of schwann cells that leads to the axon?
 This is called the [outer] mesaxon
16.
Which disease features a T cell-mediated attack on myelin?
Guillain-Barré syndrome = acute inflammatory demyelinatin
17. What protein is attacked in Multiple Sclerosis patients?
 Myelin Basic Protein (MBP) is the autoimmune target in MS
18. What is the function of neuregulin?
 Ngr1 is produced by the axon and regulates the thickness of the myelin sheath
19. What are Schmidt-Lanterman clefts? How do they appear on slides?
 Schmidt-Lanterman clefts connect the inner and outer cytoplasmic collars
 The clefts contain lysosomes and occaisonal organelles, their quantity positively correlates
with the diameter of the axon
 Show up as double rings in nerve cross sections, or as double walls on longitudinal section
20. What cell type surrounds the cell bodies of neurons in ganglia?
 Satellite cells are unmyelinated and surround just the soma of neurons in ganglia
21. Where are the two types of astrocytes located?
 Protoplasmic astrocytes are located in the gray matter
 Fibrous astrocytes are in the white matter
(ectoplasm=>goo=>gray)
(axons=>bundle=>tough=>fiber)
22. What protein do all astrocyte intermediate filaments contain?
 Glial fibrillary acidic protein (GFAP) – useful for identifying astrocyte tumors
23. What is postassium spatial buffering and who does it?
 Astrocytes regulate the extracellular K+ concentration in the brain
24.
What proteins are expressed by oligodendrocytes? How else can you tell them apart from
Schwann cells?
 PLP, MOG, Omgp
 Unmyelinated axons in the CNS do not lie in oligodendrocyte cell grooves
i. Nor do oligodendrocytes have external lamina
25.
Which are the smallest glia?

Microglia are small with few processes, and have elongated nuclei
26. Which glial cell type comes from a different progenitor than the others? How do you ID?
 Microglia come from granulocyte/monocyte progenitor (GMP) cells in bone marrow
i. You can ID them by staining for vimentin (class of intermediate filament)
27. Is the DRG in the CNS?
 Nope, the DRGs are technically peripheral
28. What part of the connective tissue of a nerve fascicle forms the blood-nerve barrier?
 The perineurium
29. How do sympathetic signals travel from spine to the kidneys? [NOT to the glands above them]
 They synapse at the aorticorenal ganglion
30. What’s the source of hindgut parasympathetics?
 These come from the sacral nerves
31. Which PNS connective tissue is made up of dense connective tissue?
 The epineurium is the outermost layer, made up of irregular DCT
32. Define neuropil:
 Axonal, dendritic, and glial processes associated with gray matter
33. What is special about circumventricular organs? What are their names?
 Circumventricular organs have a weaker blood-brain barrier
 Examples: pineal gland, area postrema (vomiting), median eminence & neurohypophysis
34. What are the differences between CNS and PNS degeneration?
 In the PNS, “Wallerian” anterograde degeneration is followed by Schwann cell dedifferentiation and proliferation
i. They then form bands of Bunger, which guide the growth of regenerating axons
 The CNS tends to scar, since microglia are less efficient than macrophages at clearing debris
i. Also known as plaque formation due to reactive gliosis
35.
What if axonal sprouts/neurites do not reestablish contact with the appropriate Schwann
cells?
 A painful traumatic neuroma forms when neurons aren’t lined up properly