The ultrastructure of Phaeocystis pouchetii (Prymnesiophyceae) vegetative colonies with special reference to the production of new mucilaginous envelope

Abstract

The ultrastructure of the vegetative colonies of Phaeocystis pouchetii (Hariot) Lager‐heim is described here for the first time from an electron microscope study. The fine structure of this colonial non‐motile form is essentially similar to that of the flagellated zoospore. The non‐motile vegetative cells of P. pouchetii lack the dimorphic body scales characteristic of most free‐living flagellated zoospores of Prymnesiophyceae. Instead, they are protected by a multilayered mucilaginous envelope (of up to 10 layers). Chrysolaminarin vesicles, thought to form from the golgi body and enclosed in a unit‐membrane, periodically protrude through the plasmalemma into the external surrounding mucilaginous layer. It is suggested that these chrysolaminarin vesicles are directly related to the deposition of mucopolysaccharide outside the cell to add new layers to the existing envelope.

Key words:

• Phaeocystis pouchetii
• mucous
• colonies
• mucilaginous envelope
• ultrastructure
• chrysolaminarin vesicles
• Tasman Bay