As one of the first to use a microscope, Levinhuk described human sperm as “with a tail, serpentine, like an eel in water.” More than three hundred years later, scientists discovered that this is an illusion of vision. Dr. Hermes Gadelha of the University of Bristol, Dr. Gabriel Corkidi of the National Autonomous University of Mexico and Dr. Alberto Darszon pioneered the reconstruction of 3D real motion in the tail of the sperm using state-of-the-art 3D microscopes and mathematical techniques.
They used a high-speed camera that shot more than 55,000 frames per second, combined with a microscope stage with piezoelectric, to move the sample up and down at a very high rate, and to capture 3D images of the sperm moving freely.
The study, published in the journal Science Advances, revealed that the sperm’s tail actually swings and swings only to one side. Sideswings seem to mean that the sperm can only swim around the circle, but the sperm has cleverly adapted to this approach and found a way to move forward.
One of the paper’s authors, Dr Gadelha, who is also a fertility expert at Polymaths Laboratory in the Department of Engineering Mathematics at the University of Bristol, said: “Human sperm scrolls at the same time as it swims, spiralling like otters frolicking in water, which balances their unilateral progress and thus moves forward.” “
“When viewed from above with a 2D microscope, the rapid, regular rotation of the sperm leads to the illusion that the tail of the sperm seems to have a symmetrical left and right movement, like ‘the eel in the water’, as Levinhuke described in the 17th century.”
The way sperm swims, as previously thought, is viewed with a microscope. Photo credit: polymath-lab.com.
“However, our findings suggest that sperm have found a swimming pattern to balance their one-way swings and cleverly solve the mathematical problem of microscales by creating symmetry in asymmetry.” Dr. Gadelha said.
“However, the rotation of human sperm is as complex as a otter: the sperm’s tail rotates around the direction of the movement, and the sperm head rotates. This is called introage in physics, just as the orbits of Earth and Mars move around the sun (in astronomy it is called the age difference). “
The real way the sperm is observed using a high-speed camera. Photo credit: polymath-lab.com.
Today, computer-aided semen analysis systems used in clinics and studies still use 2D views to observe sperm movements. As a result, they mistook the sperm’s movements for symmetry when they assessed the quality of their semen, as they did when they looked at it using the first microscope. The discovery, a ground-breaking combination of 3D microscope technology and mathematics, could offer new hope for unlocking the secrets of human reproduction.
Dr Gadelha added: “Since more than half of infertility is caused by male factors, understanding the human sperm tail provides the basis for future development of diagnostic tools to identify unhealthy sperm.” His previous work revealed the biomechanics of sperm bending, and precise rhythmic trends that describe the characteristics of sperm moving forward.
The real way for sperm to move forward is more like a rotating bottle opener. Photo credit: polymath-lab.com.
Dr. Corkidi and Dr. Darszon pioneered this 3D microscope technique for observing sperm movement. Dr Corkidi said: “This is an incredible surprise and we believe that advanced 3D microscope technology will reveal more secrets in nature. One day, the technology will be available in clinical centers. “
“This discovery will revolutionise our understanding of sperm vitality and its effects on natural fertilization,” Dr. Darszon said. Little is known about the complex environment within the female reproductive tract and how sperm movement affects fertilization. These new tools give us a glimpse of the amazing ability of sperm. “