Fertilization occurs when a sperm penetrates the outer layers of the egg and the two gametes fuse. For this process to happen, the sperm must activate the egg, triggering a series of biochemical events that allow embryo development to begin.  

This activation is primarily driven by enzymes and molecules stored in the sperm’s acrosome, a specialized pouch located at the tip of the sperm head.  

 When Is Assisted Oocyte Activation Used?  

In some cases, sperm fail to activate the egg, leading to fertilization failure. This can occur due to:  

• Globozoospermia, a rare condition where sperm lack an acrosome, preventing activation.  

• Egg-related issues, where the oocyte does not respond to sperm properly.  

AOA involves exposing the eggs to a chemical agent immediately after ICSI, mimicking the sperm’s natural activation signal. This allows the egg to mature, undergo fertilization, and progress through early embryo development.  

How Is Oocyte Activation Induced?  

The most common techniques involve:  

• Calcium ionophore treatment  

• Strontium chloride exposure  

However, due to limited data on long-term safety, assisted oocyte activation is currently prohibited in France and remains under investigation in reproductive medicine.