Ejaculation may feel like a glorious mess, as uncontrollable as an avalanche or a runaway train. In reality, it’s a tightly choreographed court dance: integrating three different branches of the nervous system, triggering cascades of contractions in smooth and striated muscles, all accompanied by the electrical storm…
Lots of human cells are specialized, but I can’t think of any that are as stripped down to a single purpose as spermatozoa. Sperm have just one job, and they’ll die doing it.
Technically, the cervix is the bottom chunk of the uterus, a circular plug-like mass of tissue dividing the uterine space from the vagina. But where most of the uterine wall is made of smooth muscle, up to 90% of the cervix is built of stiff and unyielding connective tissue. At least, it’s stiff most of the time.
A sperm’s journey from vagina to egg is only 15 centimeters long, but it’s a race with attrition.
Human vaginas don’t have the fantastical loops and blind alleys of a duck vagina, but they still have some pretty amazing shape-changing powers. Here’s how they’re put together, and how that anatomy lets them grow when they need to.
Human testes are masters of mass production, spitting out sperm at a rate of 200 million per day. But that doesn’t mean the process is fast–it takes 64 days to make a sperm. The organ keeps the count high with an assembly-line anatomy that scales up sperm development from a trickle to a flood.
Your spam folder is probably full of the offers. (Mine certainly is.) But none of the emails promising to let you “please your partner” by making you a “giant for girls” with “strong erections” say a thing about how the penis gets erect in the first place. Here’s how it really works.
Your mom helped you get through one of the most dangerous times of your life – the first few days after fertilization. She did it without even thinking about it, by stuffing the egg that helped make you full of everything you needed for those first few cell divisions. You think I’m exaggerating? I’m not.
Maybe you grew so fast it left stretch marks on your legs. Or your voice started cracking every time you got on the phone. Or you hated needing to wear a bra. Growing up means going through puberty. It’s an integral part of becoming an adult. But we still don’t know how our bodies start the process.
You were once as wrapped as snug as the pony in the picture. Before you were born, you sat wrapped inside a placenta tucked inside your mother’s womb. That placenta was the very first reproductive structure your body built, long before you built your testes or ovaries or genitalia.
Today, we scanned the skies for Earth 2, learned about a DIY science kit for cockroach mind control (or cybugs, as commenter Anarwen cleverly dubbed them), and uncovered the mysteries of the Death Star by looking exactly where you'd expect them to be: in the owner's manual.