Why does polyspermy occur in IVF?

Preincubation of oocytes and/or sperm with oviductal epithelial cells or collected oviductal fluid before IVF reduces polyspermic penetration. Recently, it was found that an abnormal zona pellucida is one of main causes of polyspermy in human eggs.

How does IVF affect polyspermy?

The polyspermy rate was affected by the number of spermatozoa used for in vitro fertilization. Insemination with 0.5-0.8, 1.0, or 1.5-2.0 X 10(6) spermatozoa/oocyte resulted in a polyspermy rate of 6%, 20%, and 32%, respectively.

What causes polyspermy?

At fertilization, eggs are exposed to multiple sperm but entry of more than one sperm causes polyploidy, polyspermy, which results in abnormal embryo development. To ensure fusion of a single sperm, the egg becomes rapidly intolerant to additional sperm.

How do you stop polyspermy?

An egg must be fertilized by a single sperm only. To prevent polyspermy, the zona pellucida, a structure that surrounds mammalian eggs, becomes impermeable upon fertilization, preventing the entry of further sperm. The structural changes in the zona upon fertilization are driven by the exocytosis of cortical granules.

When does polyspermy occur in in vitro fertilization?

This condition is called triploid syndrome, also called triploidy and is known as a diandric 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.

What happens if you have a polyspermy pregnancy?

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.

What happens during the slow block of polyspermy?

During the ‘slow block’ of polyspermy that happens 5-8 minutes after fertilization, the egg releases enzymes that alter the zona pellucida, the outer layer of the egg, and a wall is formed surrounding the egg that stops more sperm from penetrating the egg. Defects of these mechanisms,…

What does the term polyspermy mean in biology?

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.