Sperm in HD: Imaging mammalian sperm across scales and across species
Sperm are among the most structurally specialized and diverse eukaryotic cell types. Our group uses cellular cryo-electron tomography to explore the molecular landscape of mammalian sperm in a near-native state. We show that the major organelle-cytoskeleton interfaces in sperm are characterized by ordered supramolecular assemblies that are conserved across species. We resolve structural elaborations that enable mammalian sperm to swim through viscous fluids, from protofilament-bracing structures that reinforce microtubules at the nano-scale to accessory structures that impose micron-scale asymmetries on the entire assembly. Our work provides vital foundations for linking molecular structure to sperm motility, energetics, and evolution.