Lokale Kontraktionen als Ursache der Zytokinese

Fibroblast cells, glycerinated in the early stages of cytokinesis, resume cytoplasmic cleavage if incubated in a suspension containing ATP and relaxing grana (from skeletal muscle). Cleavage is due to a local contraction of the equatorial cytoplasm, while the polar parts of the cell are kept relaxed. Relaxation is brough about by a cellular relaxing system, which due telophase seems to be active at the poles whereas the system is lacking or inactive at the equatorial area. Relaxing grana added to the experimental solutions act by restoring activity to the cellular relaxing system, which had been rendered inactive by the glycerination procedure