On the dynamics of cell cleavage

A completely fluid model of cleavage dynamics is studied in which the forces exerted within the boundary structure of a cell are approximated by an effective surface tension. The hypothesis that surface tension depends in part on the concentration of tension elements implies a contraction of the surface towards the equator resulting from a dynamical instability that once triggered develops spontaneously into cleavage. The circulation of the cytoplasm induced by surface stresses collects and aligns the surface-bound tension elements into an equatorial belt. This flow may be a means of assembling a contractile ring.