In this article, we will walk you through the process of ovulation, reveal how sperm prepares to fertilise the egg, and explain the steps involved in natural or in vivo fertilisation.
Ovulation and Fertile Days
It’s clear: without ovulation, pregnancy is not possible. Ovulation is an essential process for human fertilisation to occur.
Ovulation marks the beginning of a woman’s fertile phase and typically happens once in each menstrual cycle, usually 12 to 16 days before the start of the next period. During the first stage of the menstrual cycle, oocytes (immature eggs) are present in the ovaries, and one of them matures. Ovulation is the stage when a mature egg is released from the ovary into the fallopian tube, where it can be fertilised.
A woman’s most fertile days are considered to be the two days before and after ovulation, as this is the crucial window for fertilisation.
Sperm Activation: How the Sperm Prepares to Fertilise the Egg
Though not widely known, sperm undergo a process called sperm activation to prepare for fertilisation. This stage includes sperm capacitation, which involves physiological changes that enable the sperm to fertilise the egg. These changes occur naturally when the sperm comes into contact with fluids in the female reproductive tract.
Examples of these changes include alterations in sperm movement patterns and modifications to their plasma membrane, allowing them to fuse with the egg.
The Next Step: Fertilisation
After intercourse, sperm travels through the cervical mucus, the uterine cavity, and finally reaches the fallopian tubes. Once there, the sperm must penetrate the corona radiata, a layer of cells surrounding the egg. But how does only one sperm manage to fertilise the egg? This is controlled by the zona pellucida, a protective layer of the egg. Once a single sperm passes through this layer, the egg undergoes structural changes, making it more rigid and preventing other sperm from entering. Fascinating, isn’t it?
After fertilisation, a zygote is formed, marking the start of a new life.
The entire process can occur within 24 hours after ovulation. This is known as natural or in vivo fertilisation, but fertilisation can also be performed in an assisted reproduction laboratory through in vitro fertilisation (IVF).
Want to know more about the fertilisation process? Contact Nicosia Fertility for more information!
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