Clusters of mouse embryonic stem cells called embryoid bodies more closely approximate true embryos in organization and structure than previously thought, according to researchers at the Stanford University School of Medicine.

Boston University undergraduate Jessica Rogge and associate professor Karen Warkentin, working at the Smithsonian Tropical Research Institute's laboratories in Gamboa, Panama, discovered that frog embryos at a very early developmental stage actively respond to oxygen levels in the egg—as reported in the Nov. 7, 2008 issue of the Journal of Experimental Biology. These initial responses to the environment may be critical to the frogs' long-term survival.

Children born after a frozen, thawed embryo has been replaced in the womb have higher birth weight than those born where fresh embryos were used, Danish scientists reported to the 24th annual conference of the European Society of Human Reproduction and Embryology.

The numbers of cycles of preimplantation genetic diagnosis or screening are rising steadily in Europe with over 2,700 reported in 2004 (the most recent year for which data are available).

Developing fundamental math and mechanics to explain life processes like embryo development, cellular migration and growth could open doors to a new frontier in biology, many researchers say.

A research team supervised by Universite Laval scientist Marc-Andre Sirard has identified genetic markers that allow the selection of eggs with the best chance of leading to successful pregnancy after in vitro fertilization (IVF). This finding could both increase the success rate of single embryo transfer and diminish the risk of multiple pregnancies.

In animals with separate sexes, embryos commit to becoming male or female at an early stage. Often this key decision is made by sex determination genes on the sex chromosomes.

Their findings add to the growing list of tasks carried out by an important molecule that is involved in the arrangement of everything from nerve cells to reproductive cells in the developing embryo.

About five years ago, on the islands of Samoa, most of the male Hypolimnas bolina butterflies, also known as the Eggfly or Blue Moon butterfly, disappeared. Now, scientists report that the males have made a comeback and are almost as common as females.

The metamorphosis of biology into a science offering numerically precise descriptions of nature has taken a leap forward with a Princeton team's elucidation of a key step in the development of fruit fly embryos - discoveries that could change how scientists think not just about flies, but about life in general.

Instead of preserving life, Germany’s embryo protection law has had the unintended consequence of increasing the number of foetuses killed after fertility treatment according to new figures presented at the European Society of Human Reproduction and Embryology today (Wednesday).

A new study has shown that increasing numbers of couples are travelling abroad for preimplantation genetic diagnosis (PGD), and that the main reason for this cross-border movement is the legal position in patients’ countries of origin.