Histology of the Nervous System

Question 1

Cell body of the neuron

Answer 1

Perikaryon

Question 2

Motor portion of the neuron

Answer 2

Axon

Question 3

Sensory portion of the neuron

Answer 3

Dendrite

Question 4

Basophilic granule, counterpart of the RER in neurons, the site of protein synthesis/assembly; decreases in number in the setting of nerve injury

Answer 4

Nissle body (or Nissle granule)

Question 5

This neuron process is accompanied by the following changes in the perikaryon:

• chromatolysis (DISSOLUTION of the Nissle bodies, loss of the cytoplasmic basophilia)
• increase perikaryon volume
• migration of the nucleus to a peripheral position

Answer 5

Regeneration (onset)

Question 6

This neuron process is accompanied by the following changes in the perikaryon:

• axon and myelin sheath degenerate completely
• remnants removed by macrophages
• Schwann cells proliferate, forming solid cellular column that is distal to the injury and remains attached to the effector cell

Answer 6

Degeneration of distal axonal segment (or Wallerian degeneration, or ANTEROGRADE changes)

Question 7

This neuron process is accompanied by the following changes in the perikaryon:

• distal end closest to the wound initially degrades
• remnants removed by macrophages
• growth at the distal end begins (0.5 - 3.0 mm/day) and progresses towards the columns of Schwann cells
• regeneration is successful if the sprouting axon penetrates a Schwann cell column and re-establishes contact with the effector cell

Answer 7

Regeneration of the proximal axonal segment (or RETROGRADE changes)

Question 8

Non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the CNS and PNS

Answer 8

Neuroglia (or glial cells)

Question 9

Smallest of the neuroglia, part of the mononuclear phagocytic system, found in all regions of the brain and spinal cord (CNS macrophage)

Answer 9

Microglia

Question 10

Group of neuroglia derived from extodermal tissue

Answer 10

Macroglia

(CNS macroglia

• astrocytes
• oligodendrocytes
• ependymal cells
• radial glia

PNS macroglia

• Scwhann cells
• satellite cells
• enteric glial cells)

Question 11

Most abundant type of macroglia in the CNS, have numerous arm-like projections that link neurons to their blood supply while forming the blood-brain barrier (BBB); perform a nutritive and protective function

Answer 11

Astrocytes (astroglia)

Question 12

Macroglia of the CNS that coats CNS neurons in myelin sheaths; destruction of these cells leads to multiple sclerosis (MS)

Answer 12

Oligodendrocytes

Question 13

CNS Macroglia that line the spinal cord and the ventricular system, involved in the creation and secretion of CSF; ciliated cells that are responsible for CSF circulation; also part of the BBB

Answer 13

Ependymal cells (ependymocytes)

Question 14

CNS Macroglia that arise from neuroepithelial cells after the onset of neurogenesis and further differentiate; in the developing nervous system, they function both as neuronal progenitors and as a scaffold upon which newborn neurons migrate; in the mature brain, only the cerebellum and the retina retain these characteristic cells (other parts differentiate into other neuroepithelial cells)

Answer 14

Radial glial cells

Question 15

Radial glial cells retained in the cerebellum, regulating regular synaptic plasticity

Answer 15

Bergmann glia

Question 16

Radial glial cells retained in the retina, spans the thickness of the retina and, in addition to astroglial cells, participates in a bidirectional communication with neurons

Answer 16

Radial Muller cell (or Muller cell)

Question 17

Disoder of myelin described as an immune-mediated destruction of the myelin sheaths confined to the CNS leading to slowing of conduction and neurologic dysfunction

Answer 17

Multiple sclerosis (MS or Lou-Gehrig syndrome)

Question 18

Disoder of myelin described as an immune-mediated destruction of the myelin sheaths confined to the PNS; often triggered by an infection

Answer 18

Guillan-Barre syndrome

Question 19

PNS macroglia that provides myelination the PNS; also with phagocytic activity to clear up debris

Answer 19

Schwann cells

Question 20

Small PNS macroglia that surround neurons in sensory, sympathetic, and parasympathetic ganglia; help regulate the external chemical environment; interconnected by gap junctions (like astrocytes) and respond to ATP by elevating intracellular concentration of calcium ions

Answer 20

Satellite glial cells

Question 21

Macroglia of the ENS - the intrinsic ganglia of the digestive system; thought to have many roles in the enteric system, some related to homeostasis and muscular digestive processes

Answer 21

Enteric glial cells

Question 22

Cells of the posterior pituitary that are also considered neuroglia with characteristics in common to astrocytes

Answer 22

Pituicytes

Question 23

Cells of the median eminence of the hypothalamus that are considered a subtype of ependymal cell that descend from radial glia and line the base of the THIRD VENTRICLE

Answer 23

Tanycytes

Question 24

Outermost layer of dense irregular connective tissue surrounding a peripheral nerve:

• surrounds multiple nerve fascicles as well as blood vessels which supply the nerve; as well as lymphocytes and fibroblasts that contribute to the production of collagen fibers that form the backbone of the epineurium
• provides structural support, involved in maintenance and repair

Answer 24

Epineurium

Question 25

A layer of delicate connective tissue around the myelin sheath (made by Schwann cells) of each myelinated nerve fiber

• has component cells are called endoneurial cells

Answer 25

Endoneurium, or:

• endoneurial channel
• endoneurial sheath
• endoneurial tube
• Henle sheath

Question 26

Protective sheath surrounding the fascicles that bundle axons targeting the same anatomical location

Answer 26

Perineurium