Fig. 4.
Schematic synopsis of effect of junctional length and TEER. A schematic synopsis of the observations is shown. At the state of confluence, the overall TEER was determined by the lower resistor for the paracellular pathway (RP1) compared with the resistor of the transcellular pathway (RT). During differentiation, an increase in number of cells and junctional length influenced the overall TEER until the paracellular resistor RP2 sufficiently increased when full barrier properties were achieved. The effect is clearer if you assume that TEER is following a parallel circuit. The equation to determine the TEER in such a parallel circuit clearly demonstrates that an increase in junctional length by the factor 2 leads to a reduction of TEER by 50% if all factors determining the resistor RP1 remain constant and RT is distinctly larger than Rp. This effect is diminished if RP2 is larger than the initial RP1