more girdle bands, the nucleus enlarges with DNA duplication, and organelles,
represented by Golgi body (G), are partitioned. (b) Nucleus divides, then protoplasts
are separated by invagination of the plasmalemma (Pl) across the division plane, and
vesicles (Gv) apparently derived from the Golgi body accumulate adjacent to it. (c)
Formation is completed of silicalemma (Sl) around deposition vesicles (SDV) in
which the valves will develop. (d) Opal is deposited in the SDV, then smaller SDV
form at the sides for girdle band deposition (shown in lower cell). (e) Cells separate.
(After Dawson 1973.)
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