engleski

Neuronal morphology and organization of cerebral cortex in Walker-Warburg lissencephaly type II

We analyzed morphology and dendritic development of cortical neurons, and cortical organization in 2.5-month-old infant with Walker-Warburg lissencephaly type II. This rare type of cortical malformation is characterized by loss of cortical lamination and irregular clumping of cortical neurons. The WWS cortex is disorganized, thickened, and contains a broad superficial tangentially oriented axonal plexus. Bands of connective tissue and blood vessels embedded in strands of connective tissue were found deep within disorganized cortex probably representing disorganized basal membrane. Cortical neurons were organized in irregular clums and cell islands, while glial cells were distributed both among neurons and within cell-sparse regions. White matter is disorganized and consists of numerous deep coarse bundles of axons from which scattered smaller radial bundles ascend to the cortex. Pyramidal neurons were frequently oriented obliquely, horizontally or even inverted. Apical dendrites of numerous pyramidal neurons were abruptly bended (occasionally almost at right angle). Dendritic development showed different stages of maturation within pyramidal population. Some pyramidal neurons showed poorly developed basal and apical dendrite thus resembled pyramidal neurons of late fetal stages, group of pyramidal neurons resembled those found in newborn cortex, while subset of neurons developed elaborate dendritic trees characteristic for 2.5 months-old child. Population of interneruons developed as expected for given age. Majority of nitrinergic neurons could be found at the cortex/white matter interface, which probably represent interstitial neurons (remnants of fetal subplate neurons), with few neurons scattered through cortex. Nitrinergic neurons were frequently found apposed to blood vessels. Our findings suggest two previously unnoticed changes within WWS cortex: heterochronic decoupling of dendritic maturation within the same neuronal population ; and distorted shaping of dendritic trees, probably caused by patchy displacement of basal membrane within disorganized cortex (with molecular guidance cues attached to bands of connective tissue). Supported by Croatian Ministry of Science, Education & Sports grant no. 0108115 to M.J.

development; lissencephaly type II; Golgi impregnation; migration disorder

nije evidentirano