Neuromuscular

AXONS: PATHOLOGIC CHANGES

Beaded
Giant Axonal Neuropathy
Polyglucosan bodies
Swellings
  General
  Sprouts with membrane profiles

Axon Swellings

Giant Axonal Neuropathy

From Pr P Landrieu
Many enlarged thinly myelinated, or unmyelinated, axons.
Reduced number of myelinated axons.

From Pr P Landrieu
Enlarged unmyelinated, or thinly myelinated, axons.

From Pr P Landrieu
Teased axons with focal swellings (Arrows).

From T Mozaffar
Long curly eyelashes; Curled scalp hair

Polyglucosan Bodies

H&E stain
 


VvG stain
Intramuscular axons: Focal swellings
VvG stain
 

VvG stain
Intramuscular axons: Focal swellings
PAS stain
Intramuscular nerve: Polyglucosan bodies

PAS stain
Polyglucosan bodies: In intramuscular nerve

PAS stain
 
 

Polyglucosan Bodies: Swellings in Peripheral nerve axons

Toluidine blue stain
 
Polyglucosan body
  Intra-axonal, cytoplasmic round structure
  Composed of concentric bands with varied density
  Contains: Short filaments

Toluidine blue stain
Polyglucosan bodies

Toluidine blue stain

Ultrastructure: From Robert Schmidt
Polyglucosan Bodies
Polyglucosan body
  Contains: Filaments
    Random orientnation
    Short
    Tightly packed
Polyglucosan Body Disease
Polyglucosan bodies: CNS
  Anatomic types
    Corpora amylacea
    Lafora bodies
    Bielschowsky bodies
  Contents: Abnormally branched glycogen (Amylopoectin)

Axon Swellings: Enlarged Unmyelinated axons, or Axon sprouts

Enlarged axon: Contains tubulovesicular profiles
Enlarged axon: Contains organelles & tubulovesicular profiles
Tubulovesicular profiles
Tubulovesicular profiles & Peripheral organelles

Axons: Beaded appearance

Neurofilament stains
Ultrastructure
  Axoplasm
    Neurofilaments
    Tubuloreticular
    Dark filaments
  Schwann cells
    Processes near axon
    Few axon-related SC processes
    No Büngner bands

Neurofilament (Green/Yellow) + NCAM (Red)
Many small axons have an irregular, beaded appearance
  Axon loss is apparent
    Small axons are often visualized individually, rather than in clusters
    Empty Schwann cells (Red) with no axons are present
  Remaining axons
    Most axons have associated NCAM, either co-staining or surrounding them
    Many remaining axons have a beaded appearance
  There are no large axons in this nerve fascicle
  See: Control nerve

Neurofilament (Green/Yellow) + P0 (Red)
Many small axons have an irregular, beaded appearance
  Most of these axons have no associated P0
There are rare large myelinated axons in this nerve.
See: Control nerve

Neurofilament (Green/Yellow) + MBP (Red)
Many small axons have an irregular, beaded appearance
  Most of these axons have no associated MBP
There are rare large myelinated axons in this nerve.
See: Control nerve

Axons with multiple neighboring Schwann cell processes, but not surrounded by them


From: R Schmidt
Small axon & Neighboring Schwann cell processes
  Axon (Above; Black Arrow) is associated with multiple Schwann cell processes, but not surrounded by them
    Schwann cell processes & axons are surrounded by a layer of basal lamina (Above; White arrow)
  Small axon: Contains neurofilaments (Below)

From: R Schmidt

From: R Schmidt
Small axon & Neighboring Schwann cell processes
  Associated with multiple Schwann cell processes on one side, but not surrounded by them (Above)
    Schwann cell processes, & axon above them, are surrounded by a layer of basal lamina (Above)
    Upper region of axon: Is covered by Schwann cell basal lamina but No Schwann cell processes
  Small axon: Contains neurofilaments (Below)

From: R Schmidt

Abnormal, axon with dark, punctate cytoplasm: Surrounded by several different thick Schwann cell processes


From: R Schmidt
Small axon
  Contains: Dark tubulo-reticular material
  Surrounded by: 3 Different types of Schwann cell processes
  No associated myelin

From: R Schmidt

Axon associated with a few small round Schwann cell processes


From: R Schmidt
Small axon
  Associated with a few small, round Schwann cell processes (Above)
  No associated myelin
  Axon cytoplasm: Contains probable tubuloreticular profiles, but few neurofilaments (Below)

From: R Schmidt

Axon associated almost no Schwann cell processes


From: R Schmidt
Small axon
  Associated with few Schwann cell processes (Above)
  No associated myelin
  Axon cytoplasm: Contains probable tubuloreticular profiles, but few neurofilaments (Below)

From: R Schmidt

Denervated Schwann cells with No Büngner band formation

Ultrastructure
Immunohistochemistry

From: R Schmidt
Schwann cells & processes, Multiple, with no associated axons (Above & Below)
  Associated with marked axon loss
  Individual Schwann cells & their processes
    Are surrounded by a layer of basal lamina
    No associated axons
  No Büngner bands (Clusters of multiple Schwann cells & their processes)

From: R Schmidt

From: R E Schmidt MD
Schwann cells & processes, Multiple, with no associated axons (Above)
  Associated with marked axon loss
  Individual Schwann cells & their processes
    Are surrounded by a layer of basal lamina
    No associated axons
  No Büngner bands
    Clusters of closely spaced processes: Only arise from individual Schwann cells
    Typical Büngner bands: Clusters of processes from multiple Schwann cells
Clusters of multiple Schwann cells & their processes)
  No Büngner band cells (No cells that contain both NCAM & P0) (Below)
    Denervated Schwann cells contain NCAM but not P0
    P0 (Red) is only present in myelin around 2 larger axons
  See
    Control nerve
    Nerve with Büngner band cells
      Immunohistochemistry
      Ultrastructure

NCAM (Green) + P0 (Red)

Teased Fibers

Top
  Normal myelinated axon: Long myelin internodes & Node of Ranvier (Black Arrow) at center
Middle
  Axon loss, Chronic: Multiple nuclei along teased fiber comprise Büngner Schwann cell bands
Bottom
  Wallerian Degeneration: Fiber contains myelin fragments (Ovoids; Blue Arrow)
Also see
  Segmental demyelination
  Tomaculae
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7/16/2023