Postnatal reorganization of F-actin in the central canal of the spinal cord in the rat

The ependymocytes lining the central canal of the spinal cord in rats have prominent F-actin networks in the apical cytoplasm, exhibiting significant regional heterogeneity between differing spinal levels. It is not clear when and how this regional heterogeneity develops. We examined F-actin in the central canal during postnatal development using fluorescein isothiocyanate-conjugated phalloidin staining and confocal laser scanning microscopy. The apical F-actin network in the central canal increased gradually in width during the first 2weeks after birth, peaked rapidly in the third postnatal week, then decreased gradually to adult levels. Regional differences in the F-actin network did not appear until 21 postnatal days. When the intervertebral spine movements of rats aged 14days are continuously restrained for 1week, no regional differences of F-actin arose. These findings suggest that regional differentiation of the organization of F-actin network is related to the differing kinematics of the spine at different levels.