Week 12 & 13: Histology of Neural tissue

Question 1

Typical neuron intracellular features

Answer 1

extensive cell processes, a large euchromatic
nucleus (dispersed DNA), prominent nucleolis (ribosomal RNA), extensive endoplasmic reticulum (Nissl substance, protein synthesis), a well developed cytoskeleton and axonal
microtubules (rapid transport system).

Question 2

What are there more of : Interneurons or Projection neurons?

Answer 2

Internurons - over 99%

Question 3

Internurons examples

Answer 3

Granule cells, horizontal cells, stellate cells

Question 4

Projection neurons examples

Answer 4

pyramidal cells , the ganglion cells of the retina

and the Purkinje cells of the cerebellar cortex.

Question 5

Where are capillaries form in retina?

Answer 5

Inner layers of retina

Question 6

What is fovea?

Answer 6

Only cones, raminng cell layers pushed to one side, bipolar and ganglion bodies are small

Question 7

Astrocytes

Answer 7

In CNS. two types: ( on basis of proccesses). Fibrous (in white matter), Protoplasmic (in grey matter). Medium to small - short processes have end feet. Help mediate blood-brain barrier

Question 8

Perivascular glia limitans

Answer 8

Astrocyte feet

Question 9

Superficial glial limitans

Answer 9

Astrocyte feet, pia mater????

Question 10

How to best see astrocytes?

Answer 10

Specilaised metal stains, immunological stains

Question 11

Astrocyte functions

Answer 11

mANY- mechanical support, regulation of ion and transmitter content in interstitial space, maintenance of blood brain barrier, formation of scar tissue

Question 12

Oligodendrocytes.

Answer 12

In CNS. small-medium. mainly in white matter, near proximal end of projection neuron axons. Have few processes - wrap around axons - form myelin sheath. One can meyelate several axons. Most axons in CNS are Unmyelinated.

Question 13

WHAT CELL forms myeline sheath in CNS

Answer 13

Oligodendrocytes

Question 14

Microglia

Answer 14

in CNS. small, elongated nuclei. Derive from mononuclear cells. Migratory - pass through cerebral caps to enter or leave CNS.

Question 15

Microglia functions

Answer 15

Immunological and phagocytic role

Question 16

Ependymal cells

Answer 16

in CNS. layer of CUBOIDAL cells - line ventricles and spinal canal of CNS. Villi and and cilia, NO basal lamina, joined by tight junctions

Question 17

Choroid plexus - location and function

Answer 17

In LATERAL ventricles & roofs of THIRD and FOURTH ventricles. Where most CSF made.

Question 18

Choroid plexus - layers

Answer 18

CApillary endothelium, pial cells (+loose CT), Edendyma (choroid ep).

Question 19

What are the capillaries in choroid plexus?

Answer 19

Fenestrated.

Question 20

Pia mater

Answer 20

SIngle layer of flatteneed cells, resting on basal lamina, small amount loose CT. Adheres to surface - follows, surrounds BV for short distance into brain. Adjacent to Basal lamina are astrocyte feet ends.

Question 21

Dura mater

Answer 21

Inner layer - several layers of flattened cells. Thickened outer layer - CT. Contains BV. IN skull - fused with periosteum.

Question 22

BV - Brain

Answer 22

Medium sized art + veins - in subarachnoid space. In brain - cap neetwork ++ grey mater.

Question 23

Cap in CNS

Answer 23

Cap endothelium, basal lamina, tight junctions (most)., astrocyte feet surround + intermitteant pericytes.

Question 24

Blood brain barrier

Answer 24

caps not fenestrated, tight junctions. edno surrounded by astrocyte feet = pervascular glial limitans. Junctions modulated by glial cells and possibly pericytes. Barrier = selective for cels and molecules. fenestrated in choroid plexus.

Question 25

Somatic sensory neuron

Answer 25

cell body - large euchromatic nucleus, prominent nucleolus in dorsal root ganglion or cranial nerve sensory ganglion, surrounded by satellite cells. Unipolar golgi type 1.

Question 26

Somatic sensory neuron - responding to ongoing stimulus

Answer 26

Slow, non-adaptors

Question 27

Somatic motor neuron

Answer 27

Euchromatic nucleus, prominent nucleous, many dendrites, lone long branching axon, usually mylenated, multipolar.

Question 28

Motor neurons that act on muscle spindles

Answer 28

Gamma motor neurons

Question 29

Visceral sensory neuron

Answer 29

Similar or same as somatic sensic neuron. Peripheral process in splanchnic or CN, cell body + central process .

Question 30

Visceral motor neuron

Answer 30

Pre and post ganglionic neuron. Both are multipolar and smallish. Preganglionic cell body - lateral part grey mater or CN nucleus.

Question 31

Visceral motor - Symp

Answer 31

Thoracic and upper lumbar spinal cord segments

Question 32

Visceral motor - ParaSymp

Answer 32

brain stem and sacal segments 2,3,4.

Question 33

Postganglionic cell body location in SYMp

Answer 33

symp trunk, prevertebral ganglion (short pre, long post)

Question 34

Postganglionic cell body location in ParaSYMp

Answer 34

ganglion near viscera (long pre, short post))

Question 35

Difference between pre and post ganglionic autonomic neuron

Answer 35

Pre = myelinated. Post - un

Question 36

Satellite cells

Answer 36

In PNS. small cells, surround cell bodies in somatic sensory and autonomic ganglia

Question 37

Schwann cells

Answer 37

In PNS. Multiple functions. elongated cells. wrap around segment of one axon (myelinated). or have multiple axons invaginated in them (unmyelinated)

Question 38

Perineural cells

Answer 38

PNS. flattened cells, arraranged in layers, surround collections of axons in PNs - form boundaries of the fasciles. Cells joined by tight junctions, basal lamina either side of cell layers. - produce collagen.

Question 39

Cross section of typical peripheral nerve. layers

Answer 39

Nerve fibres, 4 layers of wrapping: Schwann cell, endoneurium, perineurium, epineurium.

Question 40

Enteric Nervous system

Answer 40

Within submucosa (meissners plexus) and muscularis externa ( myenteric/auerbachs plexus) . Can act autonomously, but have input from autonomic, vesceral system.