IMMUNOHISTOCHEMICAL EXPRESSION OF CELL-ADHESION MOLECULE L1 IN HEMIMEGALENCEPHALY

We demonstrated immunohistochemically an abnormal expression of the ne ural cell adhesion molecule L1 in 10 developing brains of children wit h hemimegalencephaly (HM) aged from 36 weeks gestation to 10 years of age, comparing them with 23 controls aged from 13 weeks of gestation t o 14 years. There was dense L1 expression in focal regions of the mole cular layer beneath leptomeningeal glioneuronal heterotopia, in areas of cerebral cortex with large neurons, and in the disorganized or neur onal heterotopic sites in the white matter in HM. L1 was also heteroge neously enhanced in the abnormal cortex after 1 year of age, suggestin g that axonal growth was delayed, These changes persisted into the old er age group in the abnormal areas of cortex in HM. The cell bodies of many enlarged neurons in HM were immunopositive for L1, whereas L1 wa s usually localized to the processes of normal neurons, The delayed L1 immunoreactivity and enlaroed b L1-immunopositive neurons may be clos ely related to the pathogenesis of unilateral megalencephaly with cort ical dysplasia and heterotopia. (C) 1997 by Elsevier Science Inc.