MKI67 and neural tube defect: Here, we examined postnatal differentiation of neuronal profiles using quantitative immunohistochemistry for the intermediate cytoskeletal non-phosphorylated high-molecular-weight neurofilament (NHF) proteins; the GABAergic interneuron calcium-binding proteins (CBP) Calbindin D-28K (Calb), Calretinin (Calr) and Parvalbumin (Parv); the neuronal microtubule-associated protein doublecortin (DCX); and the cellular proliferation marker Ki-67 applied to FC tissue obtained postmortem from 28-wk gestation to 3-year-old DS and NTD cases.