Fertilization in brown algae. I. SEM and other observations on Fucus serratus.

The cell wall secreted immediately following sperm entry into an egg can be visualized by the fluorescent dye Calcofluor white. Cell wall secretion precedes nuclear fusion by 10-20 min. SEM observations of the surface of unfertilized and fertilized eggs and sperm attachment to eggs are described. These results are discussed in relation to fertilization in sea urchins and the biochemical phenomena associated with egg-sperm recognition in Fucus.