Fig. 7. The functional characterization of EGFP-positive cells demonstrated a development-dependent pattern of ion channel expression. Ramp depolarizations (150 ms from -100 mV to 50 mV, Hp -80 mV) showed that at the apolar stage (A) no voltage-dependent ion channels were detected, whereas unipolar stages (B) expressed voltage-activated outward currents. Starting from the bipolar stage, TTX hypersensitive I_Na was detected (C,D). In the early developmental stage (EDS), bipolar neurons I_Na were detected first, whereas I_Ba appeared at later stages (E). While I_Na density in bipolar neurons increased (P=0.01) during further development (F), the mean current density in multipolar neurons was less (P=0.05) than that of bipolar neurons (G).