Cell wall is required for fixation of the embryonic axis in Fucus zygotes.

Establishment of a primary developmental axis generally is thought to involve rearrangements in the plasma membrane or cytoplasm of the egg. In this report the additional requirement for cell wall in polarization of Fucus zygotes was investigated. Protoplasts of fertilized eggs were tested for their ability to establish an axis in accordance with an orienting vector of unilateral light. The results demonstrate that cell wall is not required for axis formation. However, the orientation of the axis remains labile until new cell wall is synthesized. The presence of a cell wall is an absolute requirement for axis fixation.