Structural Changes of Zoospores During and After Net Formation in Hydrodictyon reticulatum

抄録

Changes in the cell structure during and after net formation of zoospores in Hydrodictyon reticulatum were investigated by electron and fluorescence microscopy. Many small vesicles were accumulated around zoospores, and these vesicles later restricted the movement of zoospores. Immediately after cessation of the movement of polyhedral zoospores, the plasma membrane evaginated to form thread-like projections around the closely approaching regions of adacent zoospores. Then the projections seemed to fuse with the adjacent zoospores. Once the connections between the adacent cells were formed by the proections, the contact between two zoospores became progressively tighter. Cell wall materials were deposited on the plasma membrane about 10 minutes after cessation of the cell movement. Cell wall materials appeared firstly as electron-dense discontinuous patches on the plasma membrane. The patches then expanded to connect with one another, finally forming a single electron-dense cell wall layer which covered the cell surface. Netcells were finally linked by their cell walls. Cell wall substances continued to be accumulated in the space between the electron-dense cell wall layer and the plasma membrane.