Cell Division implantation Cell Division implantation
The Biology

After initial cell division, the embryo moves to the womb where it embeds. This process is called implantation.

Implantation and subsequent development of the placenta enables the embryo to obtain nutrients and oxygen from the mother. The embryo also passes carbon dioxide and other waste products to the mother via the placenta.

(above) Embryo (shown in yellow) implanting in the wall of mother’s womb

Image © Wellcome Images

How it works

If an embryo does not implant, the lining of the womb is shed. Most women know this process as their period. Embryo implantation triggers a hormone called hCG (human chorionic gonadotrophin) which stops this process.

Image © Human blastocyst,  Gillian Morriss-Kay, University of Oxford
Just before the embryo implants it is known as a blastocyst and is composed of an inner cell mass encircled by an outer cell layer of longer thinner cells (picture). While these outer cells contribute to the placenta, the inner cell mass will give rise to the embryo and is the source of embryonic stem (ES) cells. These cells are pluripotent, which means they can give rise to all cell types in the body – and they are the basis of many recent advances in regenerative medicine.

Find out more:
What are embryonic stem cells?
International Society for Stem Cell Research (ISSCR)
Scottish Stem Cell Network

Key labs that work on stem cells:
Austin Smith
Janet Rossant
Rudi Jaenisch
Shinya Yamanaka

Key labs that work on implantation:
University of Edinburgh Centre for Reproductive Biology

Recent reviews:

Recurrent implantation failure: the role of the endometrium

Wnt signaling in implantation


When development goes wrong

Occasionally, implantation happens in the wrong place. This is known as an ectopic pregnancy. If untreated this is potentially life threatening.

Dorland's Medical Dictionary for Health Consumers. © 2007 by Saunders, an imprint of Elsevier, Inc. All rights reserved. 

There are also conditions that alter the lining of the womb or endometrium, which can affect the success of implantation. One of which is called endometriosis. This painful condition occurs when the womb lining grows in the wrong place, potentially blocking the fallopian tubes.

Susceptibility to endometriosis can be inherited, but it may also to be caused by problems with the immune system. It can be treated with hormone therapy, pain relief and surgical intervention.

Find out more:
Ectopic Pregnancy


Selected research papers:
Review of possible causes of implantation failure

Implantation Dress: Details

Implantation dress: Silk jersey, silk chiffon

The white part of the dress has been embroidered to show the embryo implanting into the uterus wall (black).

Copyright Helen Storey


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