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Sperm Sniff Out Their Targets

Did you know that sperm have noses?

Scientists who study human sperm have long wondered whether human sperm could somehow sense the presence of an egg. Then, just about a decade ago, it was discovered that sperm have proteins on them that react to the presence of certain chemicals. In fact, these are the same molecules used by nerve cells in your nose when you sniff out a scent.

Obviously these noses look nothing like what we'd think of as a nose, but these chemical-sensing proteins act like noses. Researchers call these sensory devices "olfactory receptors." More recent studies have started figuring out what kind of chemical attracts a sperm.

The most effective sperm attractor is called "bourgeonal." Bourgeonal is a floral scent. When sperm sense the presence of bourgeonal, they race toward it. Their speed goes from eighteen point three micrometers per second up to a whopping thirty point one. Bourgeonal probably happens to be structurally similar to another chemical produced by a female egg.

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