Sodium current amplitude as a function of cell morphology. A, Average sodium current density (peak current divided by cell capacitance) for different types of bipolar neurons, which were classified on the basis of diameter of the synaptic terminal. Synaptic terminal diameter is one index of cell type for goldfish bipolar neurons (Sherry and Yazulla, 1993). Error bars indicate the SEM. From the left, 28, 17, and 11 cells were averaged in each class. B, Average sodium current amplitude in bipolar cells lacking an axon (left,Soma only; n = 11), in cells with an axon but without a synaptic terminal (middle,Soma + axon; n = 13), and in cells with both axon and synaptic terminal (right, Soma + axon + terminal; n = 36).