Electrorotation of axolotl embryos

The frequency dependent dielectric properties of individual axolotl embryos (Ambystoma mexicanum) were investigated experimentally utilizing the technique of electrorotation. Individual axolotl embryos, immersed in low conductivity media, were subjected to a known frequency and fixed amplitude rotating AC electric field and the ensuing rotational motion of the embryo was monitored using a conventional optical microscope. None of the embryos in the pregastrulation or neurulation stages of development exhibited any rotational motion over the field frequency range (10 Hz-5 MHz). Over the same frequency range, the embryos in the gastrulation stage of development exhibited both co-field and counterfield rotation over different ranges of the applied field frequency. Typically, the counterfield rotation exhibited a peak in the rotation spectrum at similar to I KHz while the co-field peak was located at similar to 1-2 MHz. The rotational spectral data was analyzed using a multishelled spherical embryo model to determine the electrical character of embryos during the early development stages (Stages 5-16; i.e., 16 cell through open neural plate stages). (C) 2002 Wiley-Liss, Inc.