To get a closer look at fetal development in real time and better understand the potential causes of birth defects and other health problems, scientists turned to a source you might not expect: quail eggs.
In fact, our early development as living beings is similar to that of quails, and because their embryos develop inside eggs, they can be scanned relatively easily. Bird eggs have long been favored by scientists for studying embryos.
Australian researchers used quail eggs raised to express a fluorescent peptide that binds to actin proteins that form the structure of the early embryo, called the actin cytoskeleton. This approach allowed them to observe how cells migrate and assemble to form organs.
“For the first time, we have seen high-resolution, real-time images of important early developmental processes,” says Melanie White, a developmental biologist at the University of Queensland.
“Until now, most of our knowledge about post-implantation development has come from studies of static slides, at fixed points in time.”
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The team was able to observe the very first stages of the formation of the heart, brain and spinal cord. Different microscope instruments were used to capture the fluorescent marker, which highlighted the movement of the cells.
One observation was that the neural tube, the precursor to the central nervous system, “zipped” as cells joined together.
“We saw how cells were able to push their protrusions through the open neural tube to make contact with the opposite side – the more protrusions the cells formed, the faster the tube closed,” White says.
“If this process goes wrong or is disrupted and the tube does not close properly by the fourth week of human development, the embryo will have malformations of the brain and spinal cord.”
Similar connections were made in the stem cells that would eventually form the quail’s heart.
“We were able to image the filopodia of cardiac stem cells deep in the embryo as they first came into contact, protruding and clinging to their surroundings and to each other to form the early heart,” White says.
“This is the first time anyone has managed to capture the cell’s actin cytoskeleton facilitating this contact in live imaging.”
In addition to providing a fascinating insight into the early years of life, this study is important for deepening our knowledge of how and why birth defects occur. When the connection processes fail, it can lead to problems for the child’s development.
Observing these biological transformations taking place in real time and at the smallest scale should be useful in the future to mitigate or at least identify the risk of birth defects. Many more studies on quail eggs using this process are now planned by the team.
Scientists continue to improve their models and understanding of what happens in the womb, and through this we can work to make more pregnancies as healthy as possible.
“Our goal is to find proteins or genes that can be targeted in the future or used to screen for birth defects,” White says.
“We are very excited about the possibilities that this new quail model now offers for studying development in real time.”
The research was published in Journal of Cell Biology.
