Capping it Off

Sperm are simple in structure. A head carrying precious cargo, and a tail to power it to its destination. But even something so seemingly simple requires accurate building to ensure the best chances of fertilisation. That includes the formation of the acrosome – the cap of the head full of enzymes that help to break down the outer layer of the egg and allow the sperm to penetrate for successful fertilisation. Mutations in two proteins, FAM71F1 and FAM71F2, are common in male patients with infertility because the acrosome can't form the normal half-moon shape. Shown are a ‘normal’ sperm on the left in each row and three with mutated FAM71F1 (top) and FAM71F2 (bottom) on the right. The acrosomes (green) in the mutated sperm are clearly malformed leading to fertility issues, despite there being no effects on the DNA in the sperm head (blue) or the mitochondria (magenta) that power the tail.

Written by Sophie Arthur

Sophie Arthur

former Science Communications Officer MRC LMS

Formerly a stem cell biologist, Sophie has since moved into science communication working at the MRC LMS. She also writes an award winning science and education blog Soph talks science.

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• Image adapted from work by Akane Morohoshi and Haruhiko Miyata, and colleagues
• Department of Experimental Genome Research, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Development, October 2021