Line 4:1·"Layers" is not a recognised heading for this article type.
Oxford Comma
suggestion
"Microscopically, it is composed of five different types of neurones arranged into distinct layers admixed with supporting glial cells (astrocytes, oligodendrocytes and microglia) and blood vessels."
Line 3:149·Use the Oxford comma in 'astrocytes, oligodendrocytes and microglia'.