Comparison of Histologic Characteristics of Extraocular Muscles between Rabbit and Human

J Korean Assoc EMG Electrodiagn Med 2006;8(1):46-50.
Published online May 10, 2006.

Abstract

Objectives: To evaluate differences of histologic characteristics of rabbit and human lateral rectus muscles. Methods: 15 lateral rectus and orbicularis oculi muscles from rabbits and 7 lateral rectus muscle from human during strabismus surgery were obtained and stained with ATPases (pH 4.2~4.7). Composition and diameter of type I and type II muscle fibers were calculated with Imaging Analysis. Results: Composition of rabbit lateral rectus muscle was 24.6% of type I and 75.0% of type II. Human lateral rectus muscle was composed of 56.3% type I and 43.7% type II. Composition of the type II muscle fiber was statistically predominant in rabbit but type I muscle fiber was more predominant in human. Diameter of rabbit lateral rectus, rabbit orbicularis oculi and human lateral rectus muscles is followed as type I/type II; 49.9 μm/75.9 μm, 48.0 um/73.5 μm and 100.9 μm/108.9 μm. In rabbit muscles, type II muscle fiber was significantly larger than type I. Conclusion: Composition of type II muscles was significantly larger in rabbit than human. We concluded that this result is probably due to the importance of more rapid saccadic eyeball motion of rabbit to survive to human and histologic characteristics of extraocular muscles between human and rabbit had a significant difference.

Key Words: Extraocular muscle, Histologic characteristics