"Rat liver" refers to the liver of a rat, which is a small rodent animal. It is a simple way of describing or referring to the specific organ found in rats. Full definition
To test the quality of the «blood vessels» produced, the researchers cultured a chunk of tissue made from rat liver cells using their technique. (sciencemag.org)
A procedure is described that gives almost quantitative separation of clean nuclei from a homogenate of rat liver. (science.sciencemag.org)
Ms. Minger states, in relation to plant - based proteins used in research on lab rats and referenced in the book, that «it seems those plant proteins were not only PETA approved but also the least likely to turn rat livers into tumour factories». (westonaprice.org)