Rewriting the mechanics of embryology

Scientists don't know much about the implantation stage of an embryo's development, but a recent study has uncovered the mechanics behind what they call the "black box" of development.

Embryo development in mammals is a two-stage process: In the first stage, or pre-implantation, the embryo is a small, free-floating ball referred to as a blastocyst. In post-implantation, or the second stage, the blastocyst becomes implanted in the uterus.

It's been difficult in the past for scientists to study implantation because even though blastocysts can be grown and studied independent of the body, embryology occurs too close to the mother's womb to study it in action.

According to the study's author, Professor Magdalena Zernicka-Goetz, there is a big question mark in terms of the process of post-implantation.

"During these two days, it goes from a relatively simple ball to a much larger, more complex cup-like structure, but exactly how that happens was a mystery - a black box of development. That is why we needed to develop a method that would allow us to culture and study embryos during implantation," she explained in a statement.

In order to work out the details of this "black box," Zernicka-Goetz and colleague Dr. Ivan Bedzhov created suitable conditions for implantation outside the womb using mouse cells and a gel medium. Not only is the gel's elasticity similar to uterine tissue, but also its transparency to light allowed them to film the embryo during implantation.

The holy grail of this new method is it revealed that as the blastocyst turns from a ball to a cup, it forms a never-before-seen "rosette" of wedge-shaped cells.

This discovery let researchers for the first time study embryo growth and development fully, which in turn could improve in vitro fertilization success and improve stem cell knowledge, leading to more successful regenerative medicine.