Intrasarcoplasmic Polyglucosan Inclusions in Heart and Skeletal Muscles of Long-Finned Pilot Whales (Globicephala melas) may be Age-Related

Abstract

Polysaccharide storage myopathies have been described in several animal species and are characterized by periodic acid–Schiff (PAS)-positive, diastase-resistant intrasarcoplasmic inclusions in myocytes. Skeletal and cardiac muscle samples from a subset of a single pod of stranded long-finned pilot whales (Globicephala melas) were evaluated by light and transmission electron microscopy. Twelve individuals demonstrated sporadic basophilic packets of PAS-positive, diastase-resistant complex polysaccharide material, either centrally or peripherally, in skeletal and cardiac myocytes. Few microscopic myopathic changes were found but included focal inflammation and internalized nuclei. Ultrastructurally, the inclusions consisted of loosely arranged, tangled filaments and were not membrane-bound, which is consistent with polyglucosan inclusions. Within skeletal muscle, the number of inclusions had a marginal statistically significant (P = 0.0536) correlation with length, as a proxy for age, suggesting that such inclusions in skeletal muscles may be age-related, although the cause remains unclear.