Featured Research

from universities, journals, and other organizations

Researchers Discover How Embryo Attaches To The Uterus

Date:
January 17, 2003
Source:
NIH/National Institute Of Child Health And Human Development
Summary:
Researchers funded by the National Institutes of Health have discovered how an embryo initially attaches to the wall of the uterus—what appears to be one of the earliest steps needed to establish a successful pregnancy.

Researchers funded by the National Institutes of Health have discovered how an embryo initially attaches to the wall of the uterus—what appears to be one of the earliest steps needed to establish a successful pregnancy.

Specifically, the researchers found that 6 days after an egg is fertilized, the embryo uses specialized molecules on its surface and molecules on the surface of the uterus to attach itself to the wall of the uterus.

“This discovery opens up a promising new realm of research,” said Duane Alexander, M.D., Director of the National Institute of Child Health and Human Development (NICHD). “It may lead to insight into infertility, early pregnancy loss, and perhaps to an understanding of the life-threatening complication of pregnancy known as preeclampsia.” Part of the funding for the study was provided by the NICHD, the National Institute of General Medical Sciences (NIGMS), the National Heart, Lung, and Blood Institute (NHLBI), and the National Institute of Dental and Craniofacial Research (NIDCR), all part of the National Institutes of Health.

The finding appears in the January 17th Science. The research was conducted by scientists at the University of California at San Francisco (UCSF), the Nevada Center for Reproductive Medicine in Reno, the Lawrence Berkeley National Laboratory in Berkeley, California, and the University of Wisconsin, Madison.

About 6 days after fertilization, the embryo is shaped like a sphere. The surface of the sphere is made up of a layer of specialized cells called the trophoblast. At this phase of development, the embryo is called the blastocyst. The trophoblast later gives rise to the cells that will form the fetus’ part of the placenta. (The placenta is made up of both maternal and fetal tissues.) The trophoblast is coated with a protein known as L-selectin. The wall of the uterus is coated with carbohydrate molecules. The researchers believe that as the blastocyst travels along the uterine wall, L-selectin on its surface binds to the carbohydrates on the uterine wall, until the blastocyst gradually slows to a complete stop. After this happens, the cells that later become the fetus’ contribution to the placenta develop. The placental tissue from the fetus then invades the uterine wall by sending finger-like extensions into it. These projections make contact with the maternal blood supply, becoming the pipeline through which the fetus derives nutrients and oxygen, and rids itself of carbon dioxide and wastes.

“It’s analogous to a tennis ball rolling over a table top covered with syrup,” said the study’s senior author, Susan Fisher, PhD., UCSF professor of stomatology, anatomy and pharmaceutical chemistry. “The embryo’s journey is arrested by the sticky interaction with the uterine wall.”

Dr. Fisher explained that learning about the molecular processes leading up to implantation may provide information useful for treating infertility. Some cases of unexplained infertility and early pregnancy loss are thought to derive from a failure of the trophoblast to properly attach to the uterine wall.

Findings from the study may also offer insight into preeclampsia. In this condition, pregnant women develop dangerously high blood pressure that may lead to convulsions and even death. With previous NICHD funding, Dr. Fisher and her colleagues learned that preeclampsia appears to result from a failure of placental cells to convert to blood vessel-like cells that perform their secondary function of conveying carbon dioxide, oxygen, nutrients, and wastes between the uterus and the fetus. Dr. Fisher said that if trophoblast cells fail to securely attach to the uterine wall, then it’s possible they may not successfully convert to this secondary function.

To conduct the study, researchers at UCSF collected biopsies of the endometrium-the inner lining of the uterus-from volunteers. The tissue samples were taken during the women’s monthly cycle both before the uterus is receptive to the blastocyst’s implantation and at the time when the uterus is most receptive to implantation. The researchers found that the amount of carbohydrate on the uterine wall was greatest at the time when uterine receptivity to the blastocyst was greatest.

In separate, privately funded research conducted at his Nevada clinic, Russell Foulk, M.D. then demonstrated that at the time of implantation, the blastocyst expresses much larger amounts of L-selectin than it does before implantation. (Details of Dr. Foulk's work are described more fully in the Science article.) Using the information developed by Dr. Foulk, the UCSF researchers then sought to determine how long after implantation the trophoblast retains its covering of L-selectin. To learn this, they exposed isolated trophoblasts to carbohydrate-covered beads under conditions resembling those found inside the uterus. The researchers found that the trophoblasts bonded to the carbohydrates on the beads. They also found that isolated trophoblasts bond more firmly to sections of uterine lining collected when the uterus is most receptive to implantation than to those collected when the uterine lining is least receptive. The researchers determined that the isolated trophoblasts were able to bond with the uterine carbohydrates for up to the 16th week of pregnancy.

The current study is an extension of earlier research by study author Steven Rosen, Ph.D., UCSF professor of anatomy. He had discovered that infection-fighting white blood cells known as leukocytes use the L-selectin on their surface to roll to a stop on the lining of blood vessels, which are coated with carbohydrate molecules.

“This study shows how basic research in one area can jump-start clinical studies in another,” said Judith H. Greenberg, Ph.D., acting director of NIGMS, which funds Dr. Rosen’s L-selectin research.

“The discovery of L-selectin’s role in embryo implantation means that the wealth of knowledge scientists have amassed on this sticky molecule can now be applied to questions related to early pregnancy.”

The NICHD, NIGMS, NHLBI, and NIDCR are part of the National Institutes of Health (NIH), the biomedical research arm of the federal government. NIH is part of the U.S. Department of Health and Human Services.


Story Source:

The above story is based on materials provided by NIH/National Institute Of Child Health And Human Development. Note: Materials may be edited for content and length.


Cite This Page:

NIH/National Institute Of Child Health And Human Development. "Researchers Discover How Embryo Attaches To The Uterus." ScienceDaily. ScienceDaily, 17 January 2003. <www.sciencedaily.com/releases/2003/01/030117080654.htm>.
NIH/National Institute Of Child Health And Human Development. (2003, January 17). Researchers Discover How Embryo Attaches To The Uterus. ScienceDaily. Retrieved September 23, 2014 from www.sciencedaily.com/releases/2003/01/030117080654.htm
NIH/National Institute Of Child Health And Human Development. "Researchers Discover How Embryo Attaches To The Uterus." ScienceDaily. www.sciencedaily.com/releases/2003/01/030117080654.htm (accessed September 23, 2014).

Share This



More Health & Medicine News

Tuesday, September 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Liberia Pleads for Help to Fight Ebola

Liberia Pleads for Help to Fight Ebola

AP (Sep. 22, 2014) Liberia's finance minister is urging the international community to quickly follow through on pledges of cash to battle Ebola. Bodies are piling up in the capital Monrovia as the nation awaits more help. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Ebola Doctor Says Border Controls Critical

Ebola Doctor Says Border Controls Critical

AP (Sep. 22, 2014) A Florida doctor who helped fight the expanding Ebola outbreak in West Africa says the disease can be stopped, but only if nations quickly step up their response and make border control a priority. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Global Ebola Aid Increasing But Critics Say It's Late

Global Ebola Aid Increasing But Critics Say It's Late

Newsy (Sep. 21, 2014) More than 100 tons of medical supplies were sent to West Africa on Saturday, but aid workers say the global response is still sluggish. Video provided by Newsy
Powered by NewsLook.com
Sierra Leone in Lockdown to Control Ebola

Sierra Leone in Lockdown to Control Ebola

AP (Sep. 21, 2014) Sierra Leone residents remained in lockdown on Saturday as part of a massive effort to confine millions of people to their homes in a bid to stem the biggest Ebola outbreak in history. (Sept. 20) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins