Fig. 4

Purkinje cells in FRDA show indications of both axonal remodelling and myelin disruption. Unless stated, all cerebellar images are from FRDA cases. a-d Sections are DAB (brown) immuno-labelled with Calbindin-D_28K and counterstained with haematoxylin (blue). e-q Sections are immunofluorescently labelled with Calbindin-D_28K (green) and MBP (red). The hatched areas in a, b, c, d represents the higher magnified images (i), (ii), (iii), (iv) respectively. a Axonal thickening and branching (i; black arrow). b Thickening of both axon (ii; black triangle) and recurrent collateral (ii; black arrow). c Hypertrophic axon with arciform profile (iii; black arrow). d Axonal branching with terminal sprouting (iv; black arrows). e A typically ‘normal’ Purkinje cell axon, from a control case, projecting from the perikaryon (white arrow), through the granular layer where it become myelinated (white triangle). The hatched area represents the higher magnified image f. Abnormal hypertrophic axons showing either g fragmented myelin along the axon or h complete myelin loss. i-k Purkinje cell axons showing both axonal hypertrophy and fragmented myelin distal to axon torpedoes. l A Purkinje cell torpedo absent of myelin and showing indications of sprouting (white triangle/asterisk). m Myelinated (white triangle) and non-myelinated (white arrow) Purkinje cells torpedoes. n-q Purkinje cell torpedoes with varying degrees of myelin fragmentation