While you release only a single egg each month, your partner releases millions of sperm in a single ejaculation — all with their eye on that single prize. But only one of those sperm will be crowned the victor, and the odds are stacked against fertilization. Luckily, egg and sperm have developed some pretty nifty tricks to give themselves a fighting chance.
Fig 1. The journey begins with millions of sperm cells that are released into the female reproductive tract during intercourse. The sperm cells gain their full ability to swim when they are ejaculated into the reproductive tract [ 1 ],[ 2 ].
The cytoplasm of the sperm contains NOS, which is activated along with the acrosome reaction by contact with egg jelly yellow ; above, the NOS turns green when activated and produces NO light green spray. Upon fusion with the egg, NOS is released into the egg, whereby the NO produced activates calcium release red spray. Calcium activates NOS already present in the egg, releasing more NO, which releases more calcium, and so on. In recent years, researchers have learned that nitric oxide NO is much more than an air pollutant.
To become pregnantsperm from a male has to meet an egg from a female. This can happen when a male and female have sexual intercourse, when the penis is in the vagina. If an egg has been released and is in the fallopian tube, one of these sperm may reach the membrane of the egg and get inside it.
When it comes to making a baby, the odds are stacked against any single sperm cell ever becoming a zygote through contact and penetration of a female egg. That's if a man has perfectly healthy sperm — and if he has enough of them. Let's look at the numbers: Each second, a man's body produces at least 1, sperm cells [source: Dell'Amore ].
A woman's due date is calculated from the first day of her last menstrual period. Conception occurs two weeks from that day -- that's when you're truly considered to be pregnant! Millions of sperm swim upstream on the quest to fertilize an egg.
Achieving a healthy pregnancy is a complicated, multi-stage process involving two people. Every month, the female ovulates one mature egg from one of her ovaries. Here, it will begin to move slowly down the tube towards the womb uterus.
There are many misconceptions about fertilization and pregnancy. While fertilization can seem like a complicated process, understanding it can equip you with knowledge about your own reproductive system and empower you to make decisions. Fertilization takes place in the fallopian tubeswhich connect the ovaries to the uterus.
Every month, the reproductive organs in a healthy woman prepare for pregnancy. After ovulation the egg lives for 12 to 24 hours and must be fertilised in that time if a woman is to become pregnant. The burst of oestrogen just before ovulation also works inside the neck of the uterus the cervix to make protein-rich clear jelly that covers the top of the vagina during sex.