THE SECRETION OF PHENOLIC-COMPOUNDS FOLLOWING FERTILIZATION IN ACROCARPIA-PANICULATA (FUCALES, PHAEOPHYTA)

We have used light and electron microscopy to study the secretion of p henolic substances by zygotes of the brown alga Acrocarpia paniculata (Turner) Areschoug. Phenolic compounds, packaged within vesicles known as physodes, are a major cytoplasmic component of eggs and zygotes of Acrocarpia paniculata. Physodes accumulate at the egg periphery, and were identified using several different histochemical stains. Immediat ely after fertilization, zygotes secrete large numbers of phenolic bod ies. The magnitude of phenolic release is so great that the zygote mem brane is distorted during this process. However, we have found no cyto logic evidence for endocytosis. The secreted phenolics surround the zy gote and appear to impair sperm motility by causing sperm to slow down and become motionless. As the zygote wall is secreted, the phenolics form part of the developing wall, becoming oxidized and brown in color . We conclude that phenolics play an important role in the early devel opmental processes of A. paniculata, and we discuss their possible fun ctional significance.