A study of newly excysted cells of gonyaulax polyedra (Dinophyceae) by electron microscopy

Structural development of newly excysted cells of Gonyaulax polyedra was investigated by scanning and transmission electron microscopy for the first time. Cells of known age were processed for TEM using a thin-film encapsulation technique. 0-1 hour post-excystment cells were of striking ultrastructural maturity. Unusual features included large quantities of “guanine” crystals and lipids: chloroplasts with atypical arrangement of lamellae and nuclear “blebs”. The fine structure of 8-9 h post-excystment cells closely resembled that previously described for cultured cells of this species. Thecal development, as shown by SEM, was extremely rapid; 1-2 h post-excystment cells had a complete plate tabulation and the beginnings of thecal sculpturing. Thereafter thecal architecture was consolidated and 12-13 h post-excystment cells had developed the typical heavy sculpturing characteristic of this species.