In one sentence, the biology of sex may seem simpler than the bird and the bee analogy. The sperm leaves the penis, enters the vagina, swims through the reproductive tract, and reaches the egg to fertilize it.
But it is not so simple.
It was considered a major scientific breakthrough over 300 years ago when scientists came up with the idea that a fully formed, tiny human lives inside the head of each sperm cell, which has been completely disproven and false.
Fortunately, as the human body has evolved over thousands of years to maximize fertility, so has our scientific understanding of sperm. But many of us still believe in long-standing sperm myths that have no scientific basis. Here are twelve of the most common.
- Sperm swim like Olympic athletes
A common myth is that millions, or more precisely, 20 to 300 million, heroic spermatozoa swim against each other to become the lucky little swimmers who penetrate the egg.
First, sperm do not swim directly – in most cases. Sperm movement is often classified into one of three groups known as motility.
progressive movement: actively moves in a straight line or in a large circle
non-progressive movement: all patterns except forward
motionless: not moving
In an essay for Aeon, Robert D. Martin described the course as “like a military obstacle course” and not a typical race. However, sperm require a little boost from a woman’s productive system to reach the finish line.
In fact, most of the work of movement is done by the muscles of the uterus. It guides the sperm into the fallopian tubes and towards the egg.
- Thicker sperm are more fertile
Thick semen does not mean thick sperm. This usually means a high concentration of sperm or a large number of irregularly shaped sperm. They still need the help of the female reproductive system to be safe.
When the sperm enters the vagina, it attaches to the cervical mucus. Cervical mucus does two things: protection and rejection. It protects sperm from the acidity of the vagina and rejects sperm whose shape and movement prevent them from reaching the egg.
How the female reproductive system helps sperm:
The cervix – the tissue between the vagina and the uterus – the wall expands.
The crypts, or cervical glands, increase in number and size to store sperm.
As the cervical mucus becomes thinner, it is easier for sperm to pass through.
- Sperm live only a short time after release
Not always! Life expectancy depends on where the sperm lands after ejaculation.
Sperm cells that enter the vagina after ejaculation can live for up to five days. This is due to the protective effect of cervical mucus and cervical crypts.
But if the sperm can dry out, they basically die. Sperm that falls on a cold, dry body can die after a few minutes, but in very rare cases it lasts the entire 30 minutes. Because of the heat or chemicals in the water, they may die more quickly in a hot bath or shower.
- The sperm should only go directly to the egg
It’s a pretty long journey to the egg. When the sperm leaves the penis during intercourse, it does not go directly to the uterus.
During this time, some sperm adhere to the ovarian epithelial cells in the fallopian tubes or are stored in small chambers called crypts until the first stage of fertilization, or ovulation.
Fertilization: the sperm must pass through before reaching the egg
Vagina: the first and outermost part, averaging three to six inches
cervix: a small cylindrical tube that connects the vagina to the uterus
uterus (or uterus): the place where the fetus grows during pregnancy
fallopian tubes: two tubes that connect the uterus to the ovaries and allow the sperm to move to the egg and the fertilized egg to move to the uterus.
ovaries: two organs that produce eggs that can be fertilized to become a fetus
- Sperm cells are fertile and healthy throughout a man’s life
The oldest myth is that although there is a finite number of eggs (which is true), sperm last a lifetime.
Not so fast.
Sperm production, or spermatogenesis, takes place indefinitely, but sperm quality and motility deteriorate with age.
Older men are more likely to pass on genetic mutations to their children four times faster than women, according to a study in Iceland.
A 2017 study of 1.4 million people in Sweden found a linear relationship between a man’s age and the likelihood that his children would be born with a gene mutation that neither parent had.
mn It was found that men who wear boxers have 17 percent more sperm than men who wear shorts.
But the authors of the 2018 study cautioned that their results don’t account for other factors that affect sperm production, such as the type of pants or the fabric the underwear is made of.
Get this: The body can compensate for the extra heat in the testicles by releasing hormones that stimulate the follicles that produce sperm.
So boxers are a little more sperm friendly. Wear what you are comfortable with.
- Every sperm cell is healthy and viable
Far from it.
Most sperm never reach the egg for a number of reasons. A sperm does not need to be 100% motile to be considered fertile – as long as 40% is motile, you are fertile!
And not all of those 40 percent lay eggs.
Size has a big impact on success. Multiple heads, oddly shaped tails, or missing parts make sperm unsuitable for traveling through the female reproductive tract.
Even healthy sperm cannot always survive the competition. Semen passes through the fallopian tubes and enters the interstitial fluid that surrounds the internal organs of the woman. The truth is that sperm may never be fertilized and may float around the body.
- Precocious tubers can’t get you pregnant
False! Usually. Biologically speaking, pre-cum should not contain sperm, but sperm left in the urethra can mix in the tube that carries urine and semen.
Of course, there aren’t as many as fresh sperm, but a 2011 study found that about 37 percent of samples collected from 27 men contained healthy, motile sperm.
A 2016 study of 42 men from reliable sources found that at least 17 percent of pre-abdominal specimens were filled with active, motile sperm.
Therefore, even if you use the method of attraction, some sperm will weaken and the chances of conception are less.
- When trying to conceive, more sperm is better
Just the opposite.
A high volume of semen in a single semen count is a good thing, but there are times when the benefits are reduced. The higher the sperm concentration, the more likely more sperm will fertilize the egg.
Normally, only a single-celled sperm is allowed to fertilize a single egg, and an embryo is formed. After the first sperm penetrates the protein layer surrounding the egg, this layer blocks the entry of more sperm.
But if too many sperm reach the egg, two or more, rarely, will penetrate this layer and fertilize the egg. This is called polyspermy.
Adding extra genetic material to the egg increases the risk of DNA mutations and brain disorders such as Down syndrome, as well as potentially fatal heart, spine and skull defects.
If you and your partner decide to try in vitro fertilization (IVF) to get pregnant, keep this in mind. IVF bypasses many of the reproductive functions that limit how many sperm can enter an egg, so your semen doesn’t need to have millions of sperm to be fertile.