Question

At what stage of development does implantation occur post-fertilisation?

Options

• 1st to 3rd day post-fertilisation

• 7th to 10th day post-fertilisation

• 4th to 6th day post-fertilisation

• 11th to 14th day post-fertilisation

Answer 1

Implantation occurs between the 7th and 10th day post-fertilisation. At this stage, the blastocyst makes contact with and embeds itself into the uterine endometrium. The syncytiotrophoblast layer plays a crucial role in this process, eroding the endometrial tissue and establishing the initial maternal-foetal connection that will eventually form the placenta.