The structure of the coeliac ganglion of a teleost fish Myoxocephalus scorpius.

In order to compare the structure of a teleost sympathetic ganglion with those of other vertebrates, light, fluorescence histochemical and electron microscopy were carried out on the coeliac ganglion of the scorpion fish, Myoxocephalus scorpius. In common with studies on other vertebrates, fluorescence h istochemistry distinguished two cell types: a) principal neurones which exhibited low levels of specific catecholamine fluorescence and comprise the majority of neurones in the ganglia, and b) smaller intensely fluorescent cells, some of which had processes tens of micrometers long. With the electron microscope, the principal cells were seen to make axodendritic and axosomatic synapses with axons containing mainly 30 nm agranular vesicles at the synaptic site while in other vertebrates usually only one or other synaptic association is present. Both the somata and the processes of intensely fluorescent cells contain 300-600 nm diameter vesicles many of which have electron dense cores. These cells are also innervated by axons containing 30 nm agranular vesicles.