BULBOSPINAL MUSCULAR ATROPHY

Typical patterns of denervation in muscle

H & E stain
Morphology Small angular atrophic muscle fibers Grouped muscle fiber atrophy Hypertrophic muscle fibers Split muscle fibers Internal nuclei	Pyknotic nuclear clumps: Large Degenerating & Regenerating    muscle fibers: Occasional

H & E stain	Esterase stain
Small angular muscle fibers

Muscle: Grouped atrophy

H&E stain Grouped atrophy Smaller fibers may be rounded or angular Large muscle fibers are hypertrophied

H&E stain

Muscle: NADH stain of internal architecture

NADH stain Large muscle fibers have coarse internal architecture Some small fibers are darkly stained

NADH stain

Muscle: Fiber types

ATPase, pH 9.4 Small regions of grouped atrophy Large fibers are mostly type 1 Small fibers can be either type 1 or 2

ATPase, pH 9.4

ATPase pH 4.3 stain