The Mesenchyme-Like Layer of the Fiber Cells of Trichoplax adhaerens (Placozoa), a Syncytium

The fiber cells of the middle layer of Trichoplax adhaerens are interconnected by slender extensions. Newly formed connections after mechanical disruption of the tissue studied in ultrathin sections revealed cytoplasmic continuity between the cell bodies, suggesting a syncytial organisation of the fiber cell layer. The slender extensions connecting the cell bodies are traversed by microtubules and microfilaments. The structure of rare osmiophilic cell contacts suggests a stage in the fusion of adjacent cell membranes.