Definition - What does Polyspermy mean?
Polyspermy refers to the fertilization of one egg with multiple sperm cells that result in the formation of an embryo with abnormal sets of chromosomes. This typically happens with conventional insemination where the egg and the sperm are placed in the same culture environment for fertilization.
Pregnancies that result from polyspermy often result in spontaneous miscarriages during the second or third trimesters of pregnancy and fetuses that survive until childbirth are likely to not survive beyond a few days.
Polyspermy can also complicate in vitro fertilization (IVF) by producing non-viable embryos.
FertilitySmarts explains Polyspermy
Chromosomes carry the genetic material in the cells. A healthy human cell contains 46 chromosomes arranged as 23 pairs and are known as diploid cells. When gametes (eggs and sperm) are formed, each cell receives one set, which is 23 of these chromosomes. During fertilization, these two sets from the sperm and egg unite to form an embryo with 46 chromosomes.
In polyspermy, an abnormal number of sperm fertilize a single egg, resulting in an embryo with an abnormal set of chromosomes. This condition is called triploid syndrome, also called triploidy and is known as a diandric fertilization.
In Vitro Fertilization
Polyspermy can also occur during in vitro fertilization. But with advances in IVF techniques and preimplantation genetic screening (PGS), the risk of polyspermy leading to a triploid pregnancy is minimized.
- Possible mechanism of polyspermy block in human oocytes observed by time-lapse cinematography. (2012).
- Polyspermy in in vitro fertilization of human oocytes: frequency and possible causes. (1988).