He hopes his work will help reveal how sperm behave within female bodies, an area of research that's still in its relative infancy. These kinds of innovations could one day explain the great diversity of sperm shape and size across the animal kingdom. Moreover, they could ultimately help researchers develop human infertility treatments, as well as more effective male contraceptives.
This might come as a disappointment to the courageous biologists who first looked upon sperm cells in their full glory in the 17th and 18th century, using the then-revolutionary microscope.
These early sperm scientists found themselves tasked with answering the most basic of questions, for instance: Are sperm living animals? Are they parasites? And, Does each sperm contain a tiny pre-formed adult human curled up inside?
The person with the dubious honor of being the first to study sperm in detail was Anton van Leeuwenhoek , a Dutchman who developed the early compound microscope. Van Leeuwenhoek first used his new tool to examine more chaste subjects such as bee stingers, human lice and lake water in the mids. Colleagues urged him to turn his lens to semen. But he worried it would be indecent to write about semen and intercourse, and so he stalled. Finally, in , he gave in. Hesitant to even share his findings with colleagues—let alone get a wriggler tattooed on his arm—van Leeuwenhoek hesitantly wrote to the Royal Society of London about his discovery in For example, some believed that vapor emitted by male ejaculate somehow stimulated females to make babies, while others believed that men actually made babies and transferred them to females for incubation.
That is: without being able to see sperm and eggs, these scientists were really just pulling theories out of thin air. Even after van Leeuwenhoek discovered sperm in , roughly years passed before scientists agreed on how humans formed. Under this theory, the egg—or sperm—simply provided a place for development to occur.
Discoveries throughout the s offered more evidence for this argument, including the discovery that chicks develop organs incrementally. Montgomerie notes this in the book Sperm Biology: An Evolutionary Perspective , which was edited by colleagues including Pitnick. With improvements to the microscope, midth century researchers observed embryonic development within sea urchin eggs, which are conveniently transparent. These observations continued to disprove the concept of preformation, and allowed researchers to begin asking how sperm and egg work together to create new organisms.
Sperm research also shed light on other body systems. In the s, researchers identified the protein dynein , which is responsible for sperm movement. Today we know that dynein is involved in the movement of microscopic cellular structures like cilia and flagella, which are key to many bodily functions. They believed that the egg simply provided a place for the sperm to grow. Though scientists now better understand the role that sperm plays in reproduction, our latest research has discovered that sperm have actually been fooling scientists this whole time.
One of the first microscopes was developed in the 17th century by Antonie van Leeuwenhoek. He used a blob of molten glass that he carefully ground and polished to create a powerful lens. Some of them could magnify an object times. Remarkably, a better lens was not created for over years. Anyone using a modern microscope today still makes the very same observation: sperm swim forward by wiggling their tail from side-to-side. Using state-of-the-art 3D microscopy technology, our team of researchers from the UK and Mexico, were able to mathematically reconstruct the rapid movement of the sperm tail in 3D.
We needed a super-fast camera capable of recording over 55, pictures in one second mounted in a fast oscillating stage to move the sample up and down at an incredibly high rate — effectively scanning the sperm tail while swimming freely in 3D.
What we found surprised us. We discovered that the sperm tail is in fact wonky and only wiggles on one side. In this way, the wonky one-sided stroke evens out as sperm rolls allowing it to move forwards. However, this discovery shows that sperm have developed a swimming technique to compensate for their lop-sidedness. In doing so they have also ingeniously solved a mathematical puzzle: by creating symmetry out of asymmetry.
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