CNS Histology

Question 1

Dense network of interwoven nerve fibers and their branches+synapses, together with glial filaments

Answer 1

Neuropil

Question 2

Describe cell body of large typical neuron

Answer 2

Large cell body with large, euchromatic nucleus with well-developed nucleolus

Question 3

What part of dendrites are considered “plastic”?

Answer 3

Spines

Question 4

Large, basophilic masses of free polysomes and RER

Answer 4

Nissl substance/bodies

Question 5

Initial segment where excitatory or inhibitory stimuli are initiated on a neuron

Answer 5

Axon hillock

Question 6

Distal end of axon, some of which have branching called collateral branches

Answer 6

Terminal arborization

Question 7

Ends of axons usually have small _____ which are dilaterions of branch ends and contact the postsynaptic cell

Answer 7

Telodendria

Question 8

Anatomy of chemical synapse

Answer 8

Presynaptic terminal bouton = contains mitochondria and synaptic vesicles which release NT via exocytosis

Synaptic cleft

Postsynaptic cell membrane = contains receptors for NT and ion channels to initiate new impulse

Question 9

How is an electrical synapse different from a chemical synapse?

Answer 9

Electrical synapses permit direct, passive flow of electrical current from one neuron to another; current flows via gap junctions that link the pre and post synaptic membranes

Contain connexon proteins which permit diffusioin of small molecules and electric current flow

[whereas chemical synapses require NTs to diffuse across synaptic cleft]

Question 10

3 primary types of glial cell

Answer 10

Astrocyte
Ependymal cell
Microglial cell
Oligodendrocytes

Question 11

Functions of astrocytes

Answer 11

Helps form BBB
Regulates ISF composition
Structural support to CNS
Helps neuronal dev’t
Replicates to occupy space of dying neurons

Question 12

Functions of ependymal cells

Answer 12

Lines ventricles of brain and central canal of SC

Assists in production and circulation of CSF

Question 13

Functions of microglial cells

Answer 13

Phagocytic cells that move through CNS

Protects CNS by engulfing infectious agents and other potential harmful substances

Question 14

Astrocytes have a large number of long, branching processes. Their proximal regions are reinforced with intermediate filaments made of ________

They form a vast network of delicate terminals contacting synapses+other structures.

Answer 14

GFAP (glial fibrillary acid protein)

Question 15

Function of oligodendrocytes

Answer 15

Myelinates and insulates CNS axons

Allows faster AP propagation along axons in CNS

Question 16

What glial cell type histologically appears as small cells with rounded, condensed nuclei and unstained cytoplasm/

Answer 16

Oligodendrocytes

Question 17

Ependymal cell type

Answer 17

Columnar or cuboidal

Apical end may have cilia and long microvilli to facilitate movement or absorption of CSF

[joined apically by apical junctional complexes, there is no basal lamina]

Question 18

Cell precursor to microglia

Answer 18

Monocytes

Question 19

Histological distinctions of cell layers of cerebellar cortex

Answer 19

Molecular layer = much neuropil and scattered neuronal cell bodies

Purkinje cells = extend dendrites throughout molecular layer as branching basket of nerve fibers (conspicuous in H+E stained sections)

Granular layer = contains verious small densely packed neurons and little neuropil

Question 20

Biologically older parts of the cerebral cortex, arranged into 3 layers

Answer 20

Archicortex

Question 21

Most of the cerebral cortex consists of 6 layers and is caled the ____

Answer 21

Neocortex

Question 22

The neocortex has a variety of cells, divided into what 5 morphological layers?

Answer 22

Pyramidal cells
Stellate (granule) cells
Cells of Martinotti
Fusiform cells
Horizontal cells of Cajal

Question 23

Which morphological cell type of the neocortex is characterized by small neurons with a cell body in the shape of a star?

Answer 23

Stellate (granule) cells

Question 24

Which morphological cell type of the neocortex is characterized by pyramid-shaped bodies with the apex directed towards the cortical surface?

Answer 24

Pyramidal cells

Question 25

What are the largest pyramidal cells?

Answer 25

Huge UMNs of the motor cortex = Betz cells

Question 26

Which morphological cell type of the neocortex is characterized by small polygonal cells with a few short dendrites?

Answer 26

Cells of martinotti

Question 27

Which morphological cell type of the neocortex is characterized by small and spindle-shaped but oriented parallel to surface, and are the least common cell type?

Answer 27

Horizontal cells of Cajal

Question 28

Which morphological cell type of the neocortex is characterized by spindle shaped cells oriented at right angles to the surface of the cerebral cortex?

Answer 28

Fusiform cells

Question 29

What are the 6 cortical layers from superficial to deep?

Answer 29

1. Molecular (plexiform) layer 2. Outer granular layer 3. Pyramidal cell layer 4. Inner granular layer 5. Ganglionic layer 6. Multiform cell layer

Question 30

Contents of molecular cortical layer (layer 1)

Answer 30

Dendrites and axons of cortical neurons | Sparse neuroglia and horizontal cells of Cajal

Question 31

Contents of outer granular cortical layer (layer II)

Answer 31

Dense population of small pyramidal cells and stellate cells | Axons and dendrites from deeper layers

Question 32

Contents of pyramidal cell cortical layer (layer III)

Answer 32

Pyramidal cells of moderate size predominate, martinotti cells also present

Question 33

Contents of inner granular layer of cortex (layer IV)

Answer 33

Densely packed stellate cells

Question 34

Contents of ganglionic cortical layer (layer V)

Answer 34

Large pyramidal cells and smaller numbers of stellate cells and cells of martinotti

Question 35

Contents of multiform cell cortical layer (layer VI)

Answer 35

Wide variety of cell types (small pyramidal cells, cells of martinotti, stellate cells, and fusiform cells in deeper part)

Question 36

The choroid plexus contains a thin layer of well-vascularized ____ mater covered by __________ cells

Answer 36

Pia; cuboidal

Question 37

Choroid plexus has branching system of blood vessels which run in fronds composed of a fibrous core covered by _____ epithelium, forming a villous structure Capillaries and vessels are large and thin walled. Epithelial cells rest on a _________ Long bulbous microvilli project from the epithelial cells _____ _____ between epithelial cells contribute to a blood-CSF barrier

Answer 37

Cuboidal/columnar Basal lamina Tight junctions (zona occludens)

Question 38

Structural classification of neurons and where they are found

Answer 38

Multipolar — most common, throughout CNS Bipolar — sensory of retina, olfactory, and inner ear Uni/pseudounipolar — sensory of DRG and cranial ganglia Anaxonic — regulate electrical changes of adjacent neurons (no APs of their own)

Question 39

____ = region where head of hippocampus abuts the dentate gyrus

Answer 39

Hilus