Transepithelial migration of mucosal hemocytes in Crassostrea virginica and potential role in Perkinsus marinus pathogenesis.

•Hemocyte trafficking between oyster hemolymph and mucosal surfaces was monitored.•Bi-directional migration exists between pallial mucus and hemolymph.•Trafficking rates increase following oyster exposure to Perkinsus marinus.•P. marinus may use pallial hemocytes to infect oysters via a Trojan horse strategy.