transcellular pathway

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transcellular pathway The route through cells. Substances moving across epithelia are mostly forced to pass through the epithelial cells, rather than passing between the cells (the paracellular pathway). This means that both the mucosal surface (facing the exterior) and the serosal surface (facing the interior) of the cells can act as ‘gatekeepers’, keeping out certain substances, while transporting others from one side to another, often against a concentration gradient.