Nicole Marthe Le Douarin (born 20 August 1930) is a developmental biologist known for her studies of chimeras, which have led to critical insights regarding higher animal nervous and immune systems.

In 1958, she returned to the university to continue her education at the Institut d’Embryologie Centre national de la recherche scientifique (CNRS), working with renowned embryologist Etienne Wolf.

Le Douarin continued her research on avian embryos, focusing on the interactions between the endoderm and mesoderm layers.

The use of Feulgen stain was an important turning point in Le Douarin's research, as she was now able to track specific quail cell fates in the developing embryo.

Le Douarin's work on chimeric embryos became increasingly notable, and she was able to gain international funding for her research after being appointed as Director of the C.N.R.S.

In a 1980 publication, Le Douarin detailed her process of inserting totipotent quail nerve cells into the neural primordium of a chick.

Her Feulgen stain technique allowed for the creation of a fate map detailing the migration of the quail-derived neural crest cells.

In the following years, she would gain membership to the French Academy of Science, and receive the Kyoto Prize in Advanced Technology for her work with avian chimeras.