some times two sperms can fertilize a single egg how can it
In rare instances, a phenomenon called double fertilization can occur where two sperms fertilize a single egg. This phenomenon is also known as dispermy. It typically happens during IVF (in vitro fertilization) procedures or occasionally in natural conception cases.
Here's a brief explanation of how this can happen:
1. IVF scenario: In IVF treatment, doctors may inject a single sperm into an egg to achieve fertilization. However, in some cases, two sperms might penetrate the egg simultaneously, leading to the formation of embryos with three sets of chromosomes (instead of the normal two sets). These embryos are chromosomally abnormal and usually do not result in a viable pregnancy.
2. Natural conception scenario: In very rare cases, during natural conception, two sperm cells may reach the egg at the same time and attempt to fertilize it. This can occur if the woman has multiple ovulations (releasing multiple eggs) within a short time frame or if she has sexual intercourse with different partners in quick succession. However, even if double fertilization occurs, it is highly unlikely for a viable pregnancy to develop, as such embryos would likely be chromosomally abnormal.
It's important to note that double fertilization is extremely rare and usually leads to infertility or early pregnancy loss. The resulting embryos are typically not viable due to the chromosomal abnormalities resulting from the extra set of chromosomes.
If you suspect any issues or have concerns about your fertility or pregnancy, it is always best to consult with a healthcare professional for personalized guidance and support.
In most cases, it is biologically impossible for two sperm to fertilize a single egg. This is because during normal fertilization, the process called "polyspermy" is prevented by certain mechanisms. These mechanisms ensure that only one sperm can penetrate and fertilize an egg. Here's a step-by-step explanation of fertilization and how polyspermy is prevented:
1. Fertilization begins when a mature egg is released from the ovary and travels down the fallopian tube.
2. Sperm cells are ejaculated into the during sexual intercourse and swim through the cervix, uterus, and into the fallopian tube.
3. Once in the fallopian tube, the sperm cells must swim toward the egg, navigating through the fluid.
4. Multiple sperm cells may come into contact with the outer layer of the egg known as the zona pellucida.
5. To facilitate fertilization, one sperm cell must bind and penetrate the zona pellucida.
6. Enzymes released by the sperm help to break down the zona pellucida, allowing the sperm to enter the egg.
7. Once a single sperm enters the egg, the zona pellucida undergoes changes that prevent any other sperm from binding to or entering the egg.
8. The moment the first sperm penetrates the egg, the egg's outer layer becomes impenetrable to other sperm, resulting in a block to polyspermy.
9. Inside the egg, the genetic material from the sperm and egg combine, forming a single set of chromosomes to create a unique individual.
10. After fertilization, the fertilized egg, now called a zygote, begins dividing rapidly as it moves down the fallopian tube towards the uterus, where it implants and continues to develop.
While extremely rare, there have been some documented cases of "polyspermic" fertilization in humans, where two sperm cells successfully enter the egg. However, these cases usually result in nonviable pregnancies or miscarriages due to genetic abnormalities caused by the extra set of chromosomes.
Fertilization of a single egg by two sperms is a very rare occurrence in humans and is known as polyspermy. Normally, only one sperm can successfully penetrate and fertilize an egg. However, under certain circumstances, such as in vitro fertilization or specific hormonal treatments, polyspermy can occasionally happen.
To understand how this can occur, it is important to know the process of fertilization. During sexual intercourse, millions of sperm are released into the . These sperm then swim through the cervix, uterus, and into the fallopian tubes, where the fertilization of the egg typically takes place.
Usually, after a sperm successfully enters the egg, the outer layer of the egg changes, preventing any additional sperm from entering. This is a mechanism called the zona reaction. However, in some cases, the zona reaction may not occur properly, leading to the possibility of two sperms entering the egg.
While the exact mechanism of how two sperms can fertilize a single egg is not fully understood, some theories suggest that one sperm may penetrate the outer layer of the egg but fail to enter the egg's cytoplasm, while another sperm successfully enters.
It's worth noting that polyspermy is not common and usually leads to abnormal development, resulting in early pregnancy loss or developmental abnormalities. If you have concerns or questions about this topic, it's essential to consult with a healthcare professional or a reproductive specialist for further information and guidance.