Implantation

Implantation is the attachment of a blastocyst to the uterine lining and its progressive embedding in the endometrium, establishing the maternal interface for pregnancy.

Blastocyst: A preimplantation embryo consisting of an inner cell mass, a fluid-filled cavity, and an outer trophoblast layer. Its trophoblast is the first embryonic tissue to contact the endometrium.
Fertilization: The fusion of sperm and egg that produces a zygote. It initiates the embryonic development that leads to implantation.
Implantation window: The short period when the endometrium is receptive to blastocyst attachment. Its timing helps explain why embryo transfer timing matters in fertility treatment.
Recurrent implantation failure: Repeated failure to achieve pregnancy after multiple embryo transfers in assisted reproduction. It focuses clinical attention on persistent barriers to successful implantation.
Trophoblast: The outer cell layer of a blastocyst that contributes to implantation and the fetal portion of the placenta. Trophoblast cells adhere to and penetrate the uterine lining.
Cleavage (embryo): The rapid mitotic divisions of an early embryo without overall growth in size. Cleavage transforms the zygote into the blastocyst that can implant.
In vitro fertilization: A fertility treatment in which eggs are fertilized outside the body and embryos are later transferred to the uterus. Transferred embryos must encounter a receptive endometrium to implant.
Endometrial receptivity: The capacity of the endometrium to support blastocyst attachment and early development. Its assessment seeks to identify whether timing or tissue state limits implantation.
Endometrium: The mucous membrane lining the uterus, which changes through the menstrual cycle and supports embryo implantation. Its receptive state permits attachment and embedding of the blastocyst.
Menstrual cycle: The recurring hormonal and tissue changes that prepare the reproductive system for possible pregnancy. Its ovarian and uterine phases determine the timing of endometrial receptivity.

Linked from 18 pages