Gastrin/CCK-ergic innervation of cutaneous mucous gland by the supramedullary cells of the puffer fish Takifugu niphobles

The supramedullary cells (SMCs) are spinal neurons lying at the dorsal surf ace of teleosts. In the present study, we examined whether the SMCs of the puffer fish (Takifugu niphobles) might express gastrin/cholecystokinin-immu noreactivity as observed in some other teleosts. All the SMCs were immunore active for gastrin/cholecystokinin. On the other hand, many immunoreactive varicose nerve fibers were also found terminating in the mucous glands in t he skin. In addition, immunoreactive fibers were sparsely distributed in th e epidermal layer. No neuronal cells other than the SMCs showed gastrin/cho lecystokinin-immunoreactivity centrally or peripherally. The results sugges t that gastrin/cholecystokinin-immunoreactive axons in the cutaneous mucous glands and epidermal layer are axons of the SMCs. In View of the present f indings, the possible nature of SMCs was discussed. (C) 1998 Elsevier Scien ce Ireland Ltd. All rights reserved.