Scanning and transmission electron microscopy of the phagocytosis of Treponema denticola and Escherichia coli by human neutrophils in vitro

– In the present in vitro study, scanning and transmission electron microscopy demonstrated that human neutrophils are able to phagocytize Treponema denticola cells. Two major modes of particle engulfment were detected, both of which seemed unaffected by opsonization or atmosphere (aerobic or anaerobic). The occasional finding of rather intact treponemes as long as 2 h after onset of the phagocytosis experiment, suggested that digestion could be a relatively slow process. Expulsion of digested material from the phagolysosomes to the extracellular space seemed to occur via channel-like structures in the neutrophil cytoplasm.