Cyclic changes of membrane conductivity in fertilized and activated eggs of teleost (Misgurnus fossilis) and their relation to the cell shape.

Oscillations of membrane ionic conductivity, with a period similar to cell cycle duration, were observed in fertilized and activated loach (Misgurnus fossilis) eggs. In cleaving eggs the decrease in conductivity coincided with mitosis. Synchronously with the oscillations of membrane conductivity in activated as well as in fertilized eggs, rhythmic changes in blastodisc shape occurred. The blastodisc rounded up during the period of increasing membrane conductivity and flattened while conductivity decreased. Scanning microscopy of fertilized and activated eggs revealed differences in the surface relief of rounded and flattened blastodiscs.