Life through the lens
Introduction: Zebrafish
The zebrafish, Danio rerio, breeds year-round and produces hundreds of clear-shelled eggs with the developing embryo easily visible inside. The embryos develop from one cell to a swimming fish in about two days. The visibility and speed of zebrafish embryonic development allow scientists to observe the growth of organs in very young embryos.

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Dechorionated zebrafish embryo
This zebrafish (Danio rerio) embryo has had its eggshell, or chorion, removed to improve visibility. The movie depicts the first 2.5 hours of development, during which cell division and movement are clearly visible.

Elapsed time 2.5 hours.
Fertilized zebrafish eggs were manually dechorionated, then mounted in methyl cellulose dissolved in fresh water between a slide and coverslip (using a silicon spacer). The movie was taken on an inverted compound microscope with a 10x DIC objective and digital camera.