Standalone Note here
Couched in a halo of nutrient cells, an egg smaller than the dot on an i drifts slowly down a Fallopian tube, one of a pair of narrow passages that lead from a woman's ovaries to her womb. Like a beacon guiding ships at night, the egg sends forth a calling signal. A convoy of sperm -- the remnants of an armada that was once a couple of hundred million strong -- sails into view, their long tails thrashing vigorously. Lured by the chemical signal, several hundred of the most energetic swimmers close in on the egg, their narrow tips unleashing a carefully timed sequence of biochemical salvos. One substance dissolves the jelly-like veil surrounding the egg. Another softens the egg's tough outer shell, preparing it for penetration. In the last moments before conception, a few dozen sperm race to break through the final barricade.
One and only one succeeds. The instant it tunnels its way past the egg's outer layer, an electric charge fires across the membrane and a signal from the sperm causes the eggshell to snap shut, blocking entry to any remaining contenders. The successful seed then releases its tightly coiled package of DNA, which fuses with the egg's own DNA and sets in motion a series of genetic events that culminate, nine months later, in the birth of a new human being.
That is how it is supposed to work. And for hundreds of thousands of years, without anyone knowing quite how or why, it has worked -- well enough to perpetuate the species, populate the planet and bring joy and responsibility to countless generations.
But what if it doesn't work? What if egg meets sperm and nothing happens? Human sexual reproduction can be unreliable even under optimal conditions - failing 3 out of 4 times. Factors like age or health issues can further complicate conception.
America faces an infertility crisis due to various historical and societal shifts like delayed childbearing among baby boomers and reproductive health issues stemming from past medical practices. These challenges highlight significant barriers couples face when trying to conceive.
他の言語に翻訳
原文コンテンツから
content.time.com
抽出されたキーインサイト
by Philip Elmer... 場所 content.time.com 02-21-2024
https://content.time.com/time/magazine/article/0,9171,973919,00.html深掘り質問