Immunocytochemical localization of zinc transporter 3 in the ependyma of the mouse spinal cord.

We report, for the first time, the light microscopical and ultrastructural appearance of ZnT3-immunoreactivities in the ependymal cells of the central canal of the mouse spinal cord. Light microscopy revealed the presence of ZnT3-immunoreactive (Ir) ependymal cells in 1 microm thick epon sections stained by the ABC method. The ZnT3-Ir cells were observed at all levels of the spinal cord, but were a little more numerous in lumbosacral segments than in cervicothoracic segments. The ZnT3-Ir cells had large, ovoid nuclei with abundant cytoplasm, and protruded into the lumen of the central canal. Our ultrastructural findings suggest that the ZnT3-Ir ependymal cells possess secretory activity directed towards the central canal. We propose that they may play a role in the trans-ependymal mechanism responsible for zinc homeostasis between cerebrospinal fluid and the central area of the gray matter.