SCANNING AND TRANSMISSION ELECTRON-MICROSCOPIC OBSERVATIONS ON THE CENTRAL CANAL OF THE REGENERATING TAIL SPINAL-CORD IN THE LIZARD ANOLIS-CAROLINENSIS

This paper reports an electron microscopic study of medio-proximal reg ions of the caudal regenerating spinal cord of the lizard Anolis carol inensis. After one to two months of tail regeneration, sparse sterocil iar tufts of Cerebrospinal Fluid Contacting Neurons (CSFCNs) were seen in the central canal. The canal wall was coated with microvilli and c ilia of variable length, indicating ciliogenesis in this period. The s tercocilia of CSFCNs were often linked to roundish particles 0.5-2.0 m um in diameter, which were produced from ependymal cells and, possibly , from CSFCNs. Some sterocilia at the boundary of the tuft were to som e degree smaller, suggesting that they were immature stereocilia. Thes e observation confirm the differentiation of CSFCNs within the regener ating spinal cord and suggest that stereocilia are still forming after one-two months of tail regeneration. The association of stereocilia w ith Reissner's fibre further suggests CSFCNs as being caudal mechanore ceptors.