Vegetative cells (A) and zygotes (B) of a desmid algae of the genus Spirogyra found in a water sample which stood on the bench of my kitchen window for 7 weeks after being taken from a puddle.
(B): Cells from a single filament have undergone lateral as well as scalariform conjugation. Lateral conjugation occurs when adjacent cells of the same filament fuse. The content of the cell to the lower right migrated through the conjugation tube (arrow) into the upper left cell to form the zygote. Scalariform or ladder-like conjugation occurs when cells of different filaments fuse. For this type of conjugation the content of the upper cell migrated through the conjugation tube (asterisk) into the lower cell to form the zygote.
All photographs were taken with a Canon Powershot G5 camera through a Plan-Neofluar 40x/0,75 objective attached to a Zeiss Axioskop, using brightfield illumination. Width of the filaments is about 25 µm.
Bernd
