During the embryonic stage of brain development, some neurons and synapses form properly and connect, but others don't, causing some parts and pieces to be discarded. This leaves behind dead or dying cells and requires the central nervous system to employ a type of cleanup crew.

Microglial cells take on that challenge, "ingesting" the waste, and are therefore critical for brain development. However, scientists lack a full understanding of how they populate the brain. [3]

Figure 1. Lymphatics help 'seed' early brain cells in zebrafish

Figure 1 shows in studies in mice and zebrafish, scientists had found that the precursors to microglia are formed in the yolk sac, but suspected that there may be other sources of these precursors. Using time-lapse imaging, researchers in Smith’s lab showed that microglia-like cells expressing a gene called mrc1a+ began colonizing the zebrafish brain within a day of brain formation. This was much earlier than expected.

Further imaging studies showed that the progenitor cells, which contained the mrc1a+ gene, migrated from the lymphatic vessels surrounding the brain. When the researchers destroyed the lymphoid cells, they found that the number of microglial progenitor cells was reduced. [2]

The team also noticed that the precursor cells that required the lymphatics were the ones that responded when the forming brains sustained a developmental injury.

Though Smith is excited about these findings, with his lab’s overall focus on how the nervous system is constructed, he also appreciated that this type of foundational research helps to create a blueprint that allows other researchers to understand why defects occur and how to fix them. [1]

"Understanding basic science is really important, but this is an example of where we were actually trying to go after one thing and ended up at something completely different," Smith said.

The research was supported by the Alfred P. Sloan Foundation, the National Institutes of Health, and the Indiana Spinal Cord and Brain Injury Research program with the Indiana State Board of Health. [4]

References:

1. https://swifttelecast.com/lymphatics-help-seed-early-brain-cells-in-zebrafish-sciencedaily/
2. https://biologyhub.in/lymphatic-vessels-help-seed-early-brain-cells-in-zebrafish-biology-hub/
3. https://news.knowledia.com/ZA/en/articles/lymphatics-help-seed-early-brain-cells-in-zebrafish-c47bddb2982aa09ec2d467b0bb113d132174f82c
4. https://www.sciencedaily.com/releases/2022/07/220719162102.htm

Cite this article:

Thanusri swetha J (2022), Lymphatics help 'seed' early brain cells in zebrafish, AnaTechMaz, pp.57