AN EPITHELIAL CELL-FREE PREPARATION OF THE MOTOR NERVE NET OFCYANEA(COELENTERATA; SCYPHOZOA)

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Abstract
Neurons of the motor nerve net of the jellyfish Cyanea lie between the cell bodies and muscle tails of myoepithelial cells. These myoepithelial cells are connected by septate desmosomes and, consequently, constitute a diffusion barrier and limit access to the neurons. Two techniques have been developed to remove the myoepithelial cells. One employs osmotic shock, the other, oxidation of the surface of the myoepithelial cells. The neurons remain in place and attach to the underlying mesoglea. Individual neurons retain their normal appearance and, when bathed in a saline that matches the free-ion content of the mesoglea, they retain their resting potentials and produce normal action potentials. Furthermore, the synapses continue to function normally. By supplementing the saline, these preparations can be maintained in good condition for several days. Under these culture conditions, neurons damaged during isolation produce growth cones and appear to form connections with other neurons.