The Motility of the Cells and the Extracellular Matrix of Labyrinthula -- A Colonial Organism Found on Zostera Marina

Labyrinthula is a saprophytic colonial marine protist found on Zostera marina. It consists of cells which move only within an elastic matrix thought to be synthesized and secreted by the cells themselves. Although they have no visible means of locomotion, that is, no cilia, flagella or podia, the cells exhibit movements at velocities up to
200 \mu
/min. The extracellular matrix also exhibits motility. We have found, with the help of time lapse cinemicropraphy, lamellipodia-like extracellular processes which exhibit rapid translocation and appear to form the extracellular corridors within which the cells move. Indirect antibody staining shows antimyosin specific rails extending through the extracellular corridors and branching into the lamellipodia-like processes. The rails appear to correspond to regions of birefringence observed with polarized light. Our observations have led us to construct a model which attempts to explain Labyrinthula motility.