The secret behind sperm's bendy tail
Those who are even a little familiar with the subject of biology must be knowing what the shape of a sperm is. You’ve always studied that the tail of the sperm is curvy and helps improving the motility of the male sex cell. A sperm tail consists of interconnected elastic springs to transmit the mechanical information to the distant parts of the tail. This helps the sperm to bend and swim towards an egg, a recent study revealed.
A study dating back to 50 years ago suggested that the sperm tail or flagellum is made up of a complex system of filaments, which are connected by elastic springs looking like a cylinder-like structure. For many years, scientists believed that this is the reason behind the bendy shape of a sperm’s tail.
But a new research is indicating something different. The research at the University of York has shown with the help of a mathematical model that this system is not only required to maintain the structure of the tail but also to allow it transmit the information to distant parts of tail. Researcher Hermes Gadelha said that sperm flagella with this sort of internal structure can be seen in almost all forms of life.
Remarkably, though the sperm tail has an internal structure that is well-maintained across most species, animal and human, they all create somewhat diverse movements in order to reach an egg. This advocates that the tail's structure is not the entire story to how they make their distinct tail-bending motion, noted Gadelha.To comprehend the structure of the tail, scientists inspected how different parts of the tail bent by moving the tail of a dead sperm.
Unexpectedly a movement that started near the head of the sperm, caused an opposite-direction bend at the tip of the tail, called the 'counterbend phenomenon,' signifying that mechanical information is conveyed along the interconnected elastic bands in order to create movement along the full length of the tail.
Gadelha calculated these bending movements to form a mathematical model that would help hypothesise the triggers required within the tail to make these distinct movements.
Dr Gadelha said: "The mechanism of a sperm tail first creates a sliding motion between filaments, inside this cylindrically arranged structure, finally resulting in a tail bending, a bit like the piston that converts back and forth motion in to rotation of the wheel on a train. Any one movement in this complex sequence appears to be able to trigger motion right through to the distant parts of the tail."
"The big question now is, how does the tail transmit specific biomechanical information to allow these 'rowers' to self-organise?".The research is published in Journal of the Royal Society Interface