Fig. 5.

Muscle pathology findings in homozygous ANXA11-mutant mice. a Hematoxylin and eosin (HE) staining of gastrocnemius muscle in wild-type and mutant mice. Muscle fibers in 2-month-old wild-type (+ / +) and mutant (R/R) mice were intact (left), with inclusion body myopathy becoming evident from 4 months onward (middle), as indicated by occasional dense sarcoplasmic eosinophilic aggregates (black arrow). By 9 months, mutant mice showed marked muscular dystrophy, nuclear centralization, rimmed vacuoles, and eosinophilic inclusions. N = 3 mice. Scale bar, 20 μm. b Immunofluorescence of muscle fibers stained for ANXA11 and TDP-43. In 4-month-old mutant muscle cells, ANXA11 aggregates dispersed in the sarcoplasm and sarcolemma, co-localized with TDP-43 inclusions. Scale bar, 20 μm. c Ultrastructural findings in ANXA11-P36R-associated myopathy. Longitudinal sections of muscle fibers show normal structures in wild-type mice, subsarcolemmal autophagic material in 4-month-old mutants, and Z-disc dissolution with vacuole formation in 9-month-old mutants. Middle panels show subsarcolemmal electrodense structures in small vacuoles (arrow) in 4-month-old homozygous mutants. Bottom panels show autophagic vacuoles with myelin-like debris or remnant organelles in 4- and 9-month-old muscle cells. Scale bars, 1 μm–500 nm (as indicated). Black frames in (a) and white frames in (b) & (c) denote enlarged areas