Recap for Blog 19 – Only the strongest and fittest: Jake’s love of technology leads him to a multimedia program explaining human attraction, conception and foetal development in terms of his and Zani’s personal experience. Although he finds it rather freakish to hear a BBC-type voice speak of their pheromones, hormones and the like, he is fascinated.
“Awesome. That’s more like it,” Jake mutters to himself. “Phenomenal production machine. That’s me.”
He pumps the air with his fist. “Yeah, baby!”
The sperm takes roughly two months to mature and to migrate to the scrotum where the temperature is lower than in the rest of the body – a requirement that is important for sperm to be able to fertilise an egg.
When Jake and Zani have sex, roughly 250 to 500 million sperm are discharged, but about half of them have small defects and will never reach the egg. Every sperm is a six-hundredth of a millimetre long, and the head contains all Jake’s genetic material as well as the X and Y chromosomes that determine the gender of the baby. (Not only are men phenomenal production machines, but they are the ones who determine if the baby is a boy or a girl.)
Nature determines that only the strongest and fittest sperm survive to ensure that a healthy and intelligent baby is conceived. To make sure that only the strongest, fittest and most intelligent sperm reaches the egg, Zani’s egg plays a little hard to get and places many obstacles en route. The sperm need to swim through the life-threatening acidity of the vagina; they need to forge a pathway though the thick and protective mucus in the cervix and fend off the sperm-devouring white blood cells present when she has a mild infection. But, like men, sperm love gear and each sperm wears a helmet-like cap that contains enzymes that help fight off enemies and protect the head and its valuable contents on its way to the chequered flag.
When Zani’s egg is nearly ready to be fertilised, her body releases a higher dose of oestrogen so that Zani feels sexier. And when she feels sexy, Jake doesn’t stand a chance! Her body sends out pheromones (an intoxicating natural scent) to entice her man to make love to her. He picks up the pheromones and cannot stop himself losing his head – hook, line and sinker. By this point in the baby-making process, the egg is already waiting in one of the fallopian tubes. During sex, the sperm are ejaculated at great speed and are forced towards the far end of the vagina. Unhurried and stress-free love-making releases chemicals in the vagina that prep and boost the sperm before they start moving towards the uterus. It will take the tail of the sperm about a thousand strokes to drive forward by just one centimetre.
No couch potato or lazy dweeb will ever complete this race – just the strongest and fittest! The race is a mere 15 to 18 centimetres long (the distance between the vagina and fallopian tube), but it can take several hours to complete – although the egg is hoping for a top-notch, grade-A sperm that will reach the egg within half an hour! If for some reason there is no egg waiting, a sperm can swim around for up to five days waiting for its prize to make an appearance.
When the egg does decide to saunter in, it is surrounded by a halo of nutrient cells. But there’s no stopping a determined sperm and it immediately starts to peel away the protective layers by drilling though the outer shell and, in doing so, also sheds its own protective cap, ready for skin-on-skin contact. Once the head has drilled through nearly all of the protective layer around the egg, the egg opens up to receive the sperm before the chemical make-up of its protective layer changes to make it impossible for other sperm to penetrate the honeymoon suite.
At this point, the sperm’s tail is discarded and just the head approaches Zani’s genetic material, deep inside the egg. Zani’s egg and Jake’s sperm are spontaneously drawn to each other and fuse together in a timeless dance to create a unique, one-of-a-kind human being.
This fusion can happen roughly 45 minutes after sex, but the following seven days are pivotal, and is a vulnerable time for the budding clump of cells.
“Forty-five minutes!” Jake is stunned. “Kid doesn’t waste much time, does he? Now that’s pretty cool.”
A series of graphics pop up on screen, and he leans forward to take a closer look.