if only one sperm penetrates into the zona pellucida of the ovum n other sperm which try to bind to the ovum are prevented from binding by the cortical granules secreted by exocytosis than what happens in Sextuplet? please give a detailed explanation.
In an event where only one sperm penetrates the zona pellucida of an ovum, and other sperm attempting to bind to the ovum are prevented from doing so due to the cortical granules secreted by exocytosis, a situation known as "Sextuplet" would not occur.
To provide further information on why this is the case, let's break down the fertilization process step by step:
1. Multiple sperm approach the ovum: During fertilization, multiple sperm typically approach the ovum as they swim through the female reproductive tract.
2. Penetration of the zona pellucida: The zona pellucida is a protective layer surrounding the ovum. Only one sperm is able to penetrate and pass through this layer to reach the ovum's surface. This penetration is facilitated by the release of enzymes from the sperm's acrosome, which helps break down the zona pellucida.
3. Activation of cortical granules: Once the successful sperm penetrates the ovum, it triggers a series of events within the ovum's cytoplasm. One of these events involves the release of cortical granules by exocytosis.
4. Cortical granules prevent binding of additional sperm: The cortical granules released from the ovum cause biochemical changes in the zona pellucida that make it impenetrable to other sperm. These changes can include hardening of the zona pellucida and changes in its chemical composition, making it difficult or impossible for additional sperm to bind and penetrate the ovum.
Thus, in the described scenario where only one sperm is able to penetrate the zona pellucida and bind to the ovum, the cortical granules prevent any additional sperm from successfully binding. Consequently, the presence of multiple sperm attempting to fertilize the same ovum is prevented, and Sextuplet, which refers to the development of six individuals from a single fertilization event, would not occur.