Cell migration occurs at many stages in development and can be interferred and even stopped by ionizing and electromagnetic radiation.

Could not find Reference for the electromagnetic radiation in time to do this reply sorry.

https://embryology.med.unsw.edu.au/embryology/index.php/Deve...

https://www.statpearls.com/ArticleLibrary/viewarticle/20922

https://pubmed.ncbi.nlm.nih.gov/14690282/

This man did a study showing how electromagnetc fields interfere with embryonic cell migration.

https://www.thefreelibrary.com/W.+Ross+Adey%2c+M.D.-a0163395...

Could be blood cells (?)