Pseudo Onion Bulbs

Pseudo-Onion Bulbs

Circumferential Schwann cell processes often surrounding Axons or Axon sprouts

Associations
Axons
Surrounded by: Layers of Schwann cell processes
Loss: Often severe
Regeneration & Sprouts: May be formed with regenerating axon clusters
No demyelination

H&E stain

Whorled structures: Contain nuclei & connective tissue; Myelinated axon may be in center

VvG stain

Beaded axon sprouts extend circumferentially around central large axon

Neurofilament stain

Toluidine blue stain

Whorled structures: Central myelinated axon is present within some pseudo-onion bulbs

Toluidine blue stain

Toluidine blue stain

Pseudo-Onion Bulbs
Around regenerated axons with thin myelin sheaths
Also present in regions with no axons

Toluidine blue stain

Pseudo-Onion Bulbs
Around regenerating axon clusters

Toluidine blue stain

Pseudo-Onion bulbs: Ultrastructure

Interdigitated Schwann cell processes

Schwann cell processes may surround central axon or collagen

From: Chunyu Cai

Pseudo-Onion bulbs
Multiple Schwann cell processes surround regenerated, thinly myelinated, axons

Return to: Onion bulbs

2/5/2019