This movie shows the fertilization of African clawed frog (Xenopus laevis) eggs. Sperm were added just before the filming began. The African clawed frog is used as a model organism in developmental biology because it can generate thousands of eggs at a time, and its embryos are large and transparent.

Run time 6 seconds; elapsed time one hour; light microscope: objective 1x brightfield, magnification 10x.