The immunohistochemical profile of the tethered filum terminale.

The embryopathy underlying tethering of the filum terminale is poorly understood. Knowledge of normal filum development is the foundation upon which to compare normal fila to fila from patients with tethered cord syndrome. Thirty-four fila from patients with tethered cord syndrome were immunostained with caudal neural tube developmental markers H4C4 (CD44), VIN-IS-53, AC4, FP3 and NOT1, and a panel of mature neuroglial, neural crest, epithelial and mesenchymal markers. H4C4 (CD44) and NOT1 exhibited significant alterations in immunoexpression in tethered fila compared to controls. The change in expression may be indicative of altered cell identity in the filum and constitute the predisposition to tethering.