Happy Father's Day!
I am amazed by the human bodies ability to reproduce, a miracle really,
and this is my tribute to the awe inspiring sperm,
which help to make miracles possible!
Sperm are some of the most extraordinary cells of the body, a triumph of efficient packaging, sleek design and super specialization. Sperm are extremely compact, and when sent into the forbidding environment of the female reproductive tract, they will learn on the job and change their search strategies and swim strokes as needed! Sperm are also fast and as cute as tadpoles. They have chubby teardrop heads and stylish, tapering tails, and they glide, slither, bumble and do figure-eights. A dad, from puberty onward, is pretty much a nonstop sperm bakery. In each ejaculation you can find around 150 million sperm! But out of those 150 million, only about 15% are "perfect" for baby making. Some have pinheads, others have two heads, some lack tails, a third don’t move at all.
The model sperm has three basic body segments. The head, which is a super condensed tangle of 23 chromosomes. At the tip of the sperm head is the acrosome, a specialized sack of enzymes that help the sperm penetrate through the barrier of ancillary cells and connective tissue that surrounds the ripe, ready egg. Below the head is the mid piece, which is packed with the tiny engines called mitochondria that lend the sperm its motility, and below the mid piece is the tail, a bundle of 11 entwined filaments that thrashes and propels a sperm forward.
Sperm do not really hit their stride until they are deposited in the female reproductive tract, at which point chemical signals from the vaginal and cervical mucus seem to spark them to life. They at first swim straight ahead, torpedo-style like they are 18 and off to college! If an egg has burst from its ovarian follicle and been plucked by a fallopian tube, sperm can sense its signature scent. The sperm become hyperactive, switching to a crazed figure-eight motion ideal for busting through barriers. The ovum eggs them on, signaling some to play the sacrificial kamikaze and explode their enzyme sacks prematurely, loosening the corridor for other, shapelier sperm to pass through intact. A few dozen fine-figured sperm find their way to the final barrier, the egg’s plasma membrane, where they waggle with all their crazy-eight might and beg to be chosen — but only one will be taken!
Happy Father's Day to all the great sperm that made it through and to those sperm that gave their lives for the cause!