Intravacuolar network may act as a mechanical support for Toxoplasma gondii inside the parasitophorous vacuole.

The intravacuolar network inside the parasitophorous vacuole of Toxoplasma gondii consists of an intricate system of membrane-limited tubules of uncertain role in parasite development. We propose that it is an important structural support to the maintenance of the parasites in the characteristic rosette arrangement of parasites inside the vacuole, rather than being associated with the nutrient acquisition from the host cell, as previously suggested. We based our assumptions on observations made by field emission scanning electron microscopy of an epithelial cell line (LLCMK2) infected at various time intervals. Scraping the surface of infected monolayers with Scotch tape exposed the inner organization of the parasitophorous vacuole. Ultrathin sections and freeze-fracture replicas of analogous samples were correlated with field emission observations and added new data on tubular membranes and general organization of the parasitophorous vacuole. Copyright 2005 Wiley-Liss, Inc.