What Is Oocyte Activation?

Oocyte activation is a specialised laboratory method used during ICSI procedures in assisted reproduction. The technique is based on creating artificial stimuli that mimic the natural physiological processes triggered when a sperm cell enters the oocyte. These stimuli initiate fertilisation and support the early stages of embryo development.

In some cases, even after ICSI, the oocyte does not receive a sufficiently strong activation signal — or activation does not occur at all. In such situations, oocyte activation is used to ensure fertilisation and promote normal embryo development.

Why Is Oocyte Activation Necessary?

Previous fertilisation failure
For some couples, fertilisation may not occur even after an ICSI procedure. This indicates that the oocyte did not receive an adequate activation signal from the sperm.

Sperm-related activation deficiencies
Certain sperm quality or functional issues can prevent the sperm from naturally triggering the oocyte activation process. Oocyte activation helps compensate for this deficiency.

Reduced oocyte activation capacity
In some cases, the oocyte itself may have a diminished ability to respond to activation. This may be related to the woman’s age, individual characteristics, or other biological factors.

Use of frozen–thawed oocytes
The thawing process can occasionally affect the oocyte’s natural activation potential, making additional activation necessary.

What Are the Benefits of Oocyte Activation?

• Increases the likelihood of successful fertilisation
  • Provides an opportunity to continue treatment when previous fertilisation attempts have failed
  • Supports the initiation of embryo development when it is hindered by sperm or oocyte functional issues