Donald David Brown (December 30, 1931 – May 31, 2023) was an American biologist[1] and one of the founders of molecular embryology.
[3] In 1956, he received an MD and MS from University of Chicago Medical School, writing his master's thesis on the mechanism of viral invasion.
[4][2] In 1959, he conducted postdoctoral studies with Jacques Monod at the Pasteur Institute in Paris, France.
Later, Brown and Igor Dawid investigated why frog oocytes contained many more nucleoli than did somatic cells.
They showed that the number of rDNA genes was amplified during oogenesis to support ribosome production needed for each oocyte (this discovery was independently made by Joseph Gall).