A microanatomical study of the precentral cerebral wall in human fetuses of the second trimester with ventriculomegaly and corpus callosal dysgenesis

Background: The complex structure and function of the cerebrum make it a key focus in neuroscience research. It develops from telencephalic vesicles through processes such as cell growth, division, and migration from the neuroepithelium's ventricular matrix, forming the six-layered isocortex or neocortex. Multipotent neuroepithelial cells give rise to both neuronal and glial precursors, which populate the cerebral cortex. This study investigated the number of cerebral layers and their thickness in second-trimester human fetuses with ventriculomegaly and corpus callosal dysgenesis.

Materials and methods: This study was conducted at Kasturba Medical College, Manipal, with Institutional Ethics Committee approval. The study analyzed the cerebral wall of 10 human fetuses in the second trimester. Histological sections were stained with hematoxylin and eosin, and the cortical layers were identified and measured.

Results: The mean total cerebral wall thickness was 4079.2 μm in fetuses with ventriculomegaly and 6532.8 μm in fetuses with corpus callosal dysgenesis. The morphological findings in corpus callosal dysgenesis included disorganization of the cortical plate zone, which may impact brain development, as well as the presence of dilated blood vessels.

Conclusion: This study quantified the six transient layers of the precentral cerebral wall, which are distinct during the embryonic stage and disappear at term. These layers are generally associated with specific neurodevelopmental processes. Compared with ventriculomegaly, corpus callosal dysgenesis involves distinct morphological alterations. One sample had disorganized cells in the cortical plate, and another displayed dilated blood vessels in the subventricular zone. These findings indicate significant disruptions in cortical development in corpus callosal dysgenesis.