One of the study’s more unexpected discoveries is overlapping gene expression between the kidney’s different structures, according to Eric Brunskill, PhD, the study’s lead author. Most of the thousands of genes involved in making a mammalian kidney are expressed at some level in every compartment. Previously it had been thought each kidney compartment would have unique genes driving its development, and those genes would not be expressed in the cells of other structures. This is not the case, as the research team found only a small number of genes expressed exclusively in specific kidney structures.

"Instead of it being a digital on-off pattern, where you might have many unique genes expressed in one part of the kidney but not in the other structures, we instead see a more analog picture, where almost all of the genes are expressed in the different parts but at varied levels," Dr. Brunskill said.