Figure 1. The transepithelial electrical resistance (TER) of cultured RPE is affected by serum and embryonic day 14 (E14) retinal conditioned
medium (rcSF3). RPE was isolated from E7 or E14 cultures and cultured in control media (SF3, defined in the Methods, in the
apical medium chamber and SF2, defined in the Methods, in the basal chamber) or with the following modifications: In some
cultures, the basal media was supplemented with 2% FBS (indicated by “serum”). In some cultures, the apical medium replaced
by retinal conditioned medium (indicated by rcSF3). Each data point is the average of 6–9 cultures. The standard error was
smaller than the symbols.