The study of sperm began, unsurprisingly, in a fairly bizarre fashion. In 1677, Antoni van Leeuwenhoek, a Dutch tradesman and self-taught scientist who was fascinated with microscopes, collected his semen and examined it under a microscope, where he saw millions of tiny, wriggling shapes called animalcules (little animals) swimming in the fluid. He believed that each sperm contained a miniature, preformed human being that would unfurl and develop inside the mother after being nourished by the female egg.
This theory was debunked long ago. (Thank you, science.)
A healthy sperm cell is made up of a torpedo like head that contains DNA, a middle section that’s packed with energy-providing mitochondria, and a relatively long tail that propels the sperm forward. Each sperm is .05 mm or .002 inch long. Too small to see.
In humans, normal sperm concentration ranges from 15 to >200 million per mL of semen. The WHO has officially deemed a concentration of fewer than 15 million per mL to be low, but studies show men with a sperm concentration of < 40 million per mL are considered to have impaired fertility.
In 1973, the average man in western countries had a sperm concentration of 99 million per mL. By 2011, it had fallen 47.1 million per mL.
But it’s not just the number of sperm that matters; it’s also about their shape and how they move. If sperm are swimming in a circle (non-progressive motility), it’s like revving your car’s engine in neutral – you’re not going anywhere. If they’re not moving at all, but instead are hanging out like couch potatoes with hangovers, then such immobility tends to persist. Sperm that move too slowly or sluggishly – with a forward progression of < 25 micrometers per second – simply won’t hit their target.
Sperm quality are evaluated by:
* Concentration (how densely sperm are packed in a unit volume of semen)
* Vitality (% of sperm that are alive)
* Motility (sperms movement and ♀ ability)
* Morphology (their size and shape)
info x Shanna H. Swan, PhD, author of Count Down