Conjugation in Spirogyra
by Wim van Egmond

These images show how Spirogyra conjugates, a form of sexual reproduction. Spirogyra and its relatives can be found during summer as pond scum, floating mats in ponds.

Two filaments of Spirogyra form conjugation tubes. The contents of one cell passes through the tube an fuses with a cell from the other filament.

Fertilisation occurs and a zygotre is formed. This developds into a thick walled resistant zygospore. These zygospores can withstand harsh conditions. They can survive the cold winter or when a pond dries up.
It may take a long time before new filaments start to grow. Here the start of the development into new filaments is visible as the spiral chloropasts are beginning to show.

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Images copyright: Wim van Egmond 2004 Ltd, Microscopy-UK, and all contributors 1995 onwards. All rights reserved. Main site is at with full mirror at
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