CALCITONIN-LIKE IMMUNOREACTIVITY IN THE SUBCOMMISSURAL ORGAN AND REISSNERS FIBER IN THE TELEOST CLARIAS-BATRACHUS, FROG RANA-TIGRINA AND LIZARD CALOTES-VERSICOLOR

In the CNS of vertebrates, although the subcommissural organ (SCO) has been identified as an ependymal brain gland and Reissner's fiber (RF) as a condensed product of its secretion, the exact nature of the secr etory substances has remained elusive. In the present study, immunocyt ochemical application of polyclonal antibodies against calcitonin reve aled intense immunoreactivity in the cells, cell processes and cerebro spinal spinal fluid (CSF)-contacting apical terminals of the columnar ependymal cells of the SCO in the teleost, Clarias batrachus. Intense immunoreactivity was also seen throughout the length of the RF as it e xtended along the Sylvian aqueduct, fourth ventricle and central canal of the spinal cord. Control procedures were employed to confirm the s pecificity of the immunoreaction. The results for the first time sugge st that calcitonin-like substance may be the synthetic and secretory p roduct of the SCO that may be released into the CSF or stored in the R F. Presence of calcitonin-like immunoreactivity in the SCO-RF complex of the frog Rana tigrina and the Lizard Calotes versicolor underscores wider significance of the phenomenon. In view of the potentials of th ese findings, it is felt that investigations aimed at establishing the precise nature of calcitonin-like immunoreative material in the SCO-R F complex may be rewarding. (C) 1997 Elsevier Science B.V.