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 2 weeks 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 14 days are continuously restrained for 1 week, 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.