DUAL EXCITATORY INNERVATION THROUGH THE DIFFERENT GANGLIONIC ROOTS INTHE UROPOD ADDUCTOR MUSCLE OF A CRAYFISH, PROCAMBARUS-CLARKII

Dual excitatory innervation of the crayfish (Procambarus clarkii) urop od adductor muscle, adductor exopodite (ADX), through different roots of the sixth abdominal ganglion, was confirmed histologically and elec trophysiologically. ADX contraction induced by the exciter in the thir d root (R3 exciter), showed more rapid fatigue than that by the excite r in the second root (R2 exciter), possibly owing to a more rapid depl etion of the transmitter substance in the process of neuromuscular tra nsmission. The size and position of the cell bodies of the two exciter s were not necessarily similar, whereas the dendritic fields appeared to be almost overlapping.