Study On Muscular Pathology And Expression Of Myogenin In V-pattern Strabismus With Inferior Obliqued Overation

Objective: To study the pathological changes and the number ofmyogenin-positiive activated satellite cells in the inferior oblique muscles andthe medial muscles of V-pattern strabismus with inferior obliqued overation, tofurther explore the effect of myogenin in the pathological changes of extraocularmuscle.Methods：Collected V-pattern strabismus with inferior obliqued overation (sixcases) whose operational manner were combining partial excision of the inferioroblique muscle with excision of the medial muscle and combined lateral rectusrecession were collected in our hospital in2011from Jan to Sep. The inferioroblique muscles and the medial muscles were cut during strabismus operationtreated as the strabismus group. The inferior oblique muscles and the medialmuscles were obtained from the corneal transplant donors (six cases’ of six eyes)who were no strabismus history or neuromuscular disorders, which teated as thecontrol group. Cross sections of the strabismus group and the control group werestained by HE method for observing the pathological changes with lightmicroscopy and measuring the cross-sectional area of myofibers. Myogenin(makers of satellite cells) immunoreactivity cells were stained for the expression of myogenin.Results：Both of the inferior oblique muscles and the medial muscles of V-pattern strabismus with inferior obliqued overation showed the remarkablepathological changes, whereas myofibers morphology of the control group wasnormal. Myofibers morphology of the inferior oblique muscles of the strabismusgroup were presented slightly hypertrophy, hyperplasia, thicknesses differently,arranged irregularly, stripe structure obscured; some myofiber nucleus adduction,hyaline degeneration, and a few of collagenous fibers hyperplasia. The averagecross-sectional area of myofibers was854.1±64.8μm2in the strabismus group,whereas there was no difference between the control group (719.7±80.4μm2）and the strabismus group (P>0.05). Myofibers morphology of the medialmuscles of the strabismus group were also founded stripe structure obscured，some myofiber nucleus adduction, nucleus adduction and hyaline degeneration.And it mainly expresses for the decreased of myofbers, arranged loosely andirregularly, gap increased and collagenous fibers hyperplasia.The averagecross-sectional area of myofibers was324.9±63.3μm2, whith was greatlyruduced comparing with the control group（690.8±67.3μm2）（P<0.05）. Thefrequency of myogenin-positive satellite cells of the inferior oblique muscleswas22.7%±7.03%and4.2%±0.75%in the strabismus group and the controlgroup. Significant differences existed in the expression of myogenin in twogroups (P<0.05). Again, the frequency of myogenin-positive satellite cells of themedial muscles was2.2%±0.75%and4.5%±1.05%in the strabismus group andthe control group. Significant differences also existed in the expression ofmyogenin in two groups（P<0.05）.Conclusion：The variety pathological changes were present in the inferioroblique muscles of V-pattern strabismus, particularly the amount of myogenin-positive satellite cells. The activated satellite cells may be involved ina process of myofiber regeneration and remodeling, leading to muscle strengthincreased, which caused the change of the inferior oblique function. The weakside medial muscles were appeared the decreased amount of myofibers andmyogenin-positive satellite cells, suggesting that the self-renewal and repairingprocess may be suppressed in the extracular muscle, which results in theexacerbating the histomorphology changes and weakening the medial musclefunction.