Monkey embryos grew outside the uterus
Researchers cultured monkey embryos in the laboratory long enough to observe the beginning of organ formation and the development of the nervous system.Two independent teams of researchers from the Chinese Academy of Sciences have reported on long-term extrauterine culturing of monkey embryos. The 25-day models allow the beginning of internal organ and nervous system formation to be observed in three dimensions. These stages are difficult to study during normal fetal development inside the uterus.
Supporting ectopic embryonic development is a challenging task. After a certain number of divisions, the cells fall apart. In previous studies, researchers cultured monkey blastocysts - balls of dividing cells - in petri dishes for 20 days. After that, the embryos collapsed, and scientists were unable to see the more advanced stages of their development.
In the new research, scientists used special vessels with nutrient media in which embryos could develop in a three-dimensional space corresponding to normal intrauterine development. Both groups of scientists used fertilized eggs of macaque crab-eggs (Macaca fascicularis), the experiments differed in the composition of the nutrient medium and the vessel for embryo growth.
After fertilization, the embryos formed a flat germinal disc from which three cell layers gradually developed: entoderm, mesoderm, and ectoderm. The developmental stages of the artificial embryos corresponded to the natural growth of monkey embryos.
Using a laboratory model, the researchers observed the process of formation of the neural plate - the basis of the future nervous system - from the ectoderm. As it develops, it thickens and curves into a tube, laying the foundation for the future brain and spinal column. In addition, they were able to identify the cells that would become motor neurons in the future.
The second group of scientists focused on the mesoderm cells of embryos. The researchers found that some of them differentiated into heart muscle cells, while others matured into cells found in the lining of blood and lymphatic vessels. Researchers also identified cells that developed into connective tissue and those that formed the basis of the digestive system.
Scientists believe that such studies solve two problems at once. First, they allow us to learn more about the early stages of development of complex living organisms. And secondly, they represent a small step on the way to fully extramammalian development of organisms in an artificial environment.
Sources: Lab-grown monkey embryos reveal in 3D how organs begin (nature.com), Ex utero monkey embryogenesis from blastocyst to early organogenesis: Cell