For decades, scientists have operated under the assumption that the entire brain develops from a single type of original stem cell. However, a recent study published in Nature Neuroscience proposes a new hypothesis: two distinct types of progenitor cells are necessary, with each contributing to the development of a specific part of the brain.
According to the research, one ancestral cell type gives rise to the rhombencephalon, a section of the hindbrain essential for fundamental functions such as regulating heartbeat and respiration. The second progenitor cell type, conversely, is believed to develop into two structures: the prosencephalon and the mesencephalon. These latter structures are considered key for reasoning and planning capabilities.
“"One part of the brain is fundamental for various basic functions, and the other is key for reasoning and planning"
To investigate when this dual developmental pathway emerged in evolution, the researchers searched for these two ancestral cell types across various animal species. They were identified in monkeys, chickens, fish, and even in the marine invertebrate Saccoglossus kowalevskii.
Tracing back to find a common ancestor between humans and this marine invertebrate requires going back approximately 550 million years in evolutionary history. This suggests that this dual-origin developmental process for the brain has been conserved throughout evolution and is shared among many animal species.
“"The research could help in better understanding neurodegenerative diseases"
This research also holds potential practical applications. Scientists have successfully grown rhombencephalon neurons from stem cells, which could significantly aid in understanding neurodegenerative diseases such as amyotrophic lateral sclerosis and Werdnig-Hoffmann disease.
