Orbicularis oculi: morphological changes mimicking mitochondrial cytopathy in a series of control normal muscles

Abstract

INTRODUCTION:   Orbicularis oculi (OO) muscle has recently proposed as a suitable muscle for biopsy to diagnose mitochondrial cyopathy: METHODS:   Enzyme histochemical and immunohistochemical studies were performed on OO muscle obtained from 18 patients aged 37-87 years (median 64 years), 6 males, 12 females, who were undergoing routine upper blepharoplasty surgery. RESULTS:   We confirmed the marked type II fibre (fast myosin heavy chain) predominance (89%) but also noted a different proportion and distribution of mitochondria in these fibres with occasional pseudo-'ragged-red' fibres with prominent subsarcolemmal and cytoplasmic aggregation of mitochondria. Cytochrome oxidase-negative fibr..