Printed in Great Britain ULTRASTRUCTURAL LOCALIZATION OF PHOSPHOHYDROLASES IN GAMETES, ZYGOTES AND ZOOSPORES OF

Gametes, zoospores, and zygotes of the multicellular, green alga Ulva mutabilis showed acid phosphatase reaction product in Golgi vesicles and on the membrane lining the vacuole. In addition gametes und zoospores showed enzyme reaction product on the entire surface mem-brane including the flagellar membrane. The surface membrane enzyme activity disappears from the zygote shortly after copulation and at the same time lysosome-like bodies start to appear in the cytoplasm. No alkaline phosphatase activity could be detected. The distribution of acid phosphatase is discussed in relation to the events taking place during and shortly after fertilization