JOSE CALVO / SCIENCE PHOTO LIBRARY JOSE CALVO / SCIENCE PHOTO LIBRARY
Coloured transmission electron micrograph (TEM) showing cross-sections of sperm tails. The tails have been sectioned at different points along their length. The widest pieces are from the mid-piece, which is at the start of the tail. They show residual cytoplasm (light blue), mitochondrial sheath (yellow), dense fibres (dark blue) and axoneme (red). Smaller pieces are from the principal piece, further back, and show the fibrous sheath (green), dense fibres and axoneme. The smallest pieces are from the end-piece of the sperm tail and contain only axoneme.
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