(See J. Henninger et al., "Clonal fate mapping quantifies the number of haematopoietic stem cells that arise during development," Nature Cell Biology, doi:10.1038/ncb3444, 2016.)
Image of the Day: Bloodfetti
These zebrafish blood cells express varying combinations of genes that encode for fluorescent proteins, producing a rainbow of colors that helps researchers track the progeny of individual blood stem cells.