PROFESSORS P.M. MOTTA & S. MAKABE / SCIENCE PHOTO LIBRARY PROFESSORS P.M. MOTTA & S. MAKABE / SCIENCE PHOTO LIBRARY
Fertilised egg. Coloured scanning electron micrograph (SEM) of sperm clustered on the surface of a fertilised human egg (ovum). The round egg (green) is at the zygote stage. Although the egg is already fertilised sperm are still attached to it (yellow hair-like structures). Each sperm has a head and a long tail. Coloured blue are the cumulus oophorus cells. These metabolically active cells provide the correct microenvironment for fertilisation. Magnification: x650 when printed 10 centimetres wide.
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