Posts Tagged ‘ embryos ’

Chemical that Readies Womb for Embryo Implantation Identified

Friday, February 7th, 2014

A new study from British researchers have identified a chemical, secreted by healthy embryos, that signals the womb to make itself receptive to implantation and pregnancy.  The findings have far-reaching implications for women who are struggling to achieve and sustain a pregnancy.  More from the researchers at Warwick Medical School:

Before implantation, human embryos are genetically very diverse. Some embryos will contain no normal cells at all while others contain a mixture of normal and abnormal cells. Hence, no two human embryos are the same at this early stage of development.

The article, published today in Scientific Reports, shows that high quality human embryos secrete a chemical, trypsin, which renders the lining of the womb supportive of implantation. This chemical signal is deregulated in low quality embryos and causes an alarm response in the womb, which leads to either rescue or elimination of the embryo.

Professor Jan Brosens explained, “This is important, because if the lining of the womb is not well prepared for pregnancy you may find that abnormal embryos will implant or high quality embryos will not be supported. Both scenarios can lead to pregnancy loss or even late pregnancy complications, such as foetal growth restriction or preterm birth.”

“Speaking in terms of an entrance exam; a poorly prepared womb will either make the test too rigorous or too lax – decreasing the chances of a successful pregnancy.”

Approximately 15% of clinically recognised pregnancies miscarry, attributed to the invasive nature of the human embryo and prevalence of chromosomal errors.

Professor Siobhan Quenby said, “This work adds to a growing body of evidence that assessment and optimisation of the lining of the womb may be the only effective way in preventing infertility and pregnancy complications.”

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Genetic Testing of Embryos Spurs Ethics Debate

Tuesday, February 4th, 2014

The debate over the morality of performing genetic tests on embryos–and deciding not to use those carrying  deadly genetic disorders for potential pregnancies–continues, as a New York Times report explains:

….The procedure also raises unsettling ethical questions that trouble advocates for the disabled and have left some doctors struggling with what they should tell their patients. When are prospective parents justified in discarding embryos? Is it acceptable, for example, for diseases like GSS [Gerstmann-Straussler-Scheinker disease], that develop in adulthood? What if a gene only increases the risk of a disease? And should people be able to use it to pick whether they have a boy or girl? A recent international survey found that 2 percent of more than 27,000 uses of preimplantation diagnosis were made to choose a child’s sex.

In the United States, there are no regulations that limit the method’s use. The Society for Assisted Reproductive Technology, whose members provide preimplantation diagnosis, says it is “ethically justified” to prevent serious adult diseases for which “no safe, effective interventions are available.” The method is “ethically allowed” for conditions “of lesser severity” or for which the gene increases risk but does not guarantee a disease.

There is no question that the method’s use is increasing rapidly, though no group collects comprehensive data, said Dr. Joe Leigh Simpson, vice president for research at the March of Dimes and past president of the American Society for Reproductive Medicine.

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New IVF Technique Could Mean Higher Success Rates

Monday, May 20th, 2013

A new method of performing in vitro fertilization (IVF), one of the most common medical interventions used to help infertile couples become pregnant, has shown promising initial success rates.  Developed in London, the new technique involves taking time-lapse photos of embryos as they develop, enabling doctors to choose the most “low-risk” embryos–with the lowest probability of having chromosomal abnormalities or other defects that could stop their growth–to transfer into a hopeful mother-to-be.  NBC News has more:

In their study, published in the journal Reproductive BioMedicine Online, the team’s chances of producing a successful live birth after in-vitro fertilization (IVF) were increased by 56 percent using the new technique compared to the standard method of selecting embryos that look best through a microscope.

“In the 35 years I have been in this field, this is probably the most exciting and significant development that can be of value to all patients seeking IVF,” said Simon Fishel, a leading fertility doctor and director at the IVF clinic operator CARE Fertility where the technique is being developed.

Independent scientists not involved in the work welcomed it as a significant advance but said full randomized controlled trials – the gold standard in medicine – should be conducted before it is adopted as mainstream practice.

“This paper is interesting because we really do need to make advances in selecting the best embryos created during IVF,” said Allan Pacey of Sheffield University, chair of the British Fertility Society.

“The idea of monitoring embryo development more closely is being used increasingly in clinics around the world and so it is good to see the science involved submitted to peer review and publication,” he added. “All too often, developments in IVF are trumpeted as advances when they remain unproven.”

Experts say that today, as many as 1 to 2 percent of babies in the Western world are conceived through IVF. The standard methods of selecting embryos are based largely on what they look like through a microscope, and many IVF cycles fail because the embryo chosen and transferred to the womb fails to develop.

Image: Petri dish containing embryos, via Shutterstock

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Researchers: Stem Cells Can Generate Human Eggs

Monday, February 27th, 2012

Scientists at Massachusetts General Hospital have discovered a way to use ovarian stem cells to create human eggs, a finding that may offer new hope to women struggling with infertility.  The New York Times reports:

Women are born with a complement of egg cells that must last throughout life. The ability to isolate stem cells from which eggs could be cultivated would help not only with fertility but also with biologists’ understanding of how drugs and nutrition affect the egg cells.

The new research, by a team led by the biologist Jonathan L. Tilly, depends on a special protein found to mark the surface of reproductive cells like eggs and sperm. Using a cell-sorting machine that can separate out the marked cells, the team obtained reproductive cells from mouse ovaries and showed that the cells would generate viable egg cells that could be fertilized and produce embryos.

They then applied the same method to human ovaries donated by women at the Saitama Medical Center in Japan who were undergoing sex reassignment because of a gender identity disorder. As with the mice, the team was able to retrieve reproductive cells that produced immature egg cells when grown in the laboratory. The egg cells, when injected into mice, generated follicles, the ovarian structure in which eggs are formed, as well as mature eggs, some of which had a single set of chromosomes, a signature of eggs and sperm. The results were published online Sunday by the journal Nature Medicine.

Image: Human cell cultures, via Shutterstock.

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