At cyst formation in the 'giant' unicellular green alga Acetabularia, each cyst contains a single nucleus which subsequently undergoes several rounds of mitosis prior to gamete formation. Initially the nuclei form a syncytium which separates into individual gametes. This section shows a stage in gametogenesis where the syncytium has just started to divide into uninuclear gametes, and the formation of flagella from paired centrioles is in progress. See Woodcock and Miller, 1973. Ultrastructural features of the life cycle of Acetabularia I Gametogenesis. Proptoplasma 77, 313-319.