Ultrastructural studies of extraocular muscles in ocular motility disorders

Abstract

Thirty eight extraocular muscle biopsies obtained from thirty patients (1 normal and 29 affected with various kinds of ocular motility disorders such as strabismus, Duane's syndrome, paralysis), were studied by electron microscopy. Except for the control biopsy considered as normal, they showed: atrophy, disorganization of myofilaments, double Z-disks, rods, curving arrays of myofibrils, concentrically disposed electron-dense sarcotubules, clusters of mitochondria with numerous modifications of their cristae, and subsarcolemmal inclusions, such as dense bodies, laminated bodies, lipofuscin granules and lipid droplets. In addition, subsarcolemmal granulo-fibrillar aggregates, characterized by periodic granulated foci spaced at about 120 nm intervals, were seen in all the biopsies, even in that of the control case. The authors stress the pecularity of the granulo-fibrillar aggregates which, up to now, have never been described in skeletal muscles and the function of which in the extraocular muscles fibers is impossible to define. They point out the difficulty in determining if the motility disturbances may be related to the various changes observed in extraocular muscles of squinting eyes.

Extraocular Muscles in Patients With Infantile Nystagmus

“…Similar changes were described in EOMs from patients with strabismus, but the same features also were seen in control EOMs. 24 Thus, care must always be taken when interpreting electron micrographs from EOMs as they have many histologic characteristics distinct from other skeletal muscles. 25 The present analysis focused on changes that were quantifiable and clearly visible using standard light microscopy.…”

Altered Protein Composition and Gene Expression in Strabismic Human Extraocular Muscles and Tendons

“…8,9,14–20 Unless specific molecules were probed, most abnormalities were subtle and to some extent also present in normal control tissues, or they could not be identified at all. However, failure to demonstrate alterations at the level of histology and even ultrastructure does not rule out the possibility of differences in molecular composition.…”

The Oculomotor Systems Ability to Adapt to Structural Changes Caused by the Process of Senescence: A Review

“…Age-related changes in extraocular muscle fibres are well-documented (Berard-Badier, Pellissier, Toga, Mouillac, & Berard, 1978;Bruenech, 2008;Clark & Demer, 2002;Miller, 1975;McKelvie, Friling, Davey, & Kowal, 1999). These changes consist mainly of fragmentation and loss of myofilaments (see Figure 4A), along with accumulation of lipofuscin (see Figure 4B) and changes in mitochondrial content.…”