The development of new molecular tools including GFP, and major advances in imaging technology including fluorescence microscopy, have made possible the mapping of the cell lineage of "Caenorhabditis elegans" including its embryo. This technique of fate mapping is used to study cells as they differentiate and gain specified function. Merely observing a cell as it becomes differentiated during embryogenesis provides no indication of the mechanisms that drive the specification. The use of molecular techniques, including gene and protein knock downs, knock outs and overexpression allows investigation into the mechanisms of fate determination. Improvements in imaging tools including live confocal microscopy and super resolution microscopy allow visualization of molecular changes in experimentally manipulated cells as compared to controls. Transplantation experiments can also be used in conjunction with the genetic manipulation and lineage tracing. Newer cell fate determination techniques include lineage tracing performed using inducable Cre-lox transgenic mice, where specific cell populations can be experimentally mapped using reporters like brainbow, a colorful reporter that is useful in the brain and other tissues to follow the differentiation path of a cell.