In this case of semi-identical, or sesquizygotic, twins, the egg is thought to have been fertilised simultaneously by two sperm before it divided. If one egg is fertilised by two sperm, it results in three sets of chromosomes, rather than the standard two - one from the mother and two from the father.
If more than one sperm fuses—a condition called polyspermy—multipolar or extra mitotic spindles are formed, resulting in faulty segregation of chromosomes during cell division; nondiploid cells are produced, and development usually stops.
-For the nearly 5,000 sperm that make it into the utero-tubal junction, around 1,000 of these reach the inside of the Fallopian tube. -For the 1,000 sperm entering the tube, only around 200 actually reach the egg. -In the end, only 1 lucky sperm out of this group of 200 actually penetrates and fertilizes the egg!
Sperm with many tails also have Macrocephaly, meaning that multiple tailed sperm come with the same problems as their big-headed associates: their chromosomal makeup is abnormal and therefore results in failed pregnancies and miscarriages when meeting with the egg.
Superfecundation twins: When a woman has intercourse with two different men in a short period of time while ovulating, it's possible for both men to impregnate her separately. In this case, two different sperm impregnate two different eggs.
Hint: Generally, two sperms do not fertilize the same egg. When one sperm comes in contact with the zona pellucida layer, there occur changes in the membrane, which prevent further entry of sperms. Two sperm fertilizing the same is very rare and occurs in very rare cases and embryos usually do not survive.
The anti-bodies are present in all of the body fluids. So, at ejaculation, when the sperm are combined with the fluids of the prostate and the seminal vesicles, the anti-bodies within these fluids attach to the surface of the sperm and cause the sperm to clump together.
Normal sperm have an oval head with a long tail. Abnormal sperm have head or tail defects — such as a large or misshapen head or a crooked or double tail. These defects might affect the ability of the sperm to reach and penetrate an egg. However, having a large percentage of misshapen sperm isn't uncommon.
Environmental toxins, lifestyle choices such as smoking, and stresses all damage DNA. Even with damaged DNA, sperm can fertilize eggs.
How many sperm do you need to get pregnant? It takes just one sperm to fertilize a woman's egg. Keep in mind, though, for each sperm that reaches the egg, there are millions that don't. On average, each time men ejaculate they release nearly 100 million sperm.
In short, if you have unprotected sex at any time around or during your ovulation, you stand a very real chance of getting pregnant. The CDC estimates that women under 30 who have regular unprotected sexual intercourse are more than 75% likely to become pregnant within a year.
While there is no definite age at which male ejaculation ceases, it has been suggested that it may happen when a man reaches his late 40s or early 50s. It is important to note, however, that this is not a universal rule and some men may continue to ejaculate at a later age.
Although it's unusual, she sometimes releases more than one egg. If she has sex with different men, then different sperm cells from different men might each fertilize an egg and heteropaternal (different father) superfecundation might occur. These babies will be half siblings.
Once the sperm enters the reproductive system, it can take about 30-45 minutes to reach the egg. For this, it is important to have a healthy sperm which has the right kind of motility to reach the egg and fertilize it. Once inside the body of a woman, a healthy sperm can live up to 2-5 days.
There is a chance that two different sperm cells will fertilize both eggs. A woman gives birth to twins in this case. Fraternal twins or non-identical twins are the terms used to describe these types of twins.
Check for Semen
The easiest way to confirm whether sperm has gone inside your body is to check for semen. If you or your partner notice the presence of semen during or after intercourse, it is a sign that sperm has likely entered the body.
Sperm DNA can be damaged during sperm production and transport. This damage is known as DNA fragmentation. High levels of sperm DNA fragmentation have been shown to double the likelihood of a miscarriage occurring (Source – Men and Miscarriage Research).
A trained expert checks your sperm count, their shape, movement, and other characteristics. In general, if you have a higher number of normal-shaped sperm, it means you have higher fertility. But there are plenty of exceptions to this. A lot of guys with low sperm counts or abnormal semen are still fertile.
In this case of semi-identical, or sesquizygotic, twins, the egg is thought to have been fertilised simultaneously by two sperm before it divided. If one egg is fertilised by two sperm, it results in three sets of chromosomes, rather than the standard two - one from the mother and two from the father.
Eat a healthy diet.
Choose plenty of fruits and vegetables, which are rich in antioxidants — and might help improve sperm health.
First, the zona pellucida contains sperm receptors which are specific for human sperm. Second, once the membrane has been penetrated by the sperm, it becomes impermeable to penetration by other sperm.
As men get older it is also usual for their semen to become slightly thinner with less volume being produced at ejaculation. It is therefore quite normal if there appear to be clumps of jelly-like globules in your semen and there is nothing to worry about here.
The next time you have sex, the number of sperms is not as much as the first time, but the quality of sperm remains stable, and that quantity is enough for fertilization to occur. This proves that having sex twice in a row is still possible to get pregnant if there is no reasonable protection.