Rat embryonic stem cells (rESCs) are a commonly used animal model in stem cell research and developmental biology. rESCs are usually isolated from blastocysts derived from the inner cell mass of 3.5-day-old embryos and have the potential to generate all cell types present in the body. They can be grown in serum-free media, without a feeder layer, in the presence of leukaemia inhibitory factor (LIF) and bone morphogenetic protein (BMP)-4, making them an excellent model.

rESCs are a very good tool to understand many aspects of cell and developmental biology, such as cell cycle regulation, cell interactions during development and control of gene expression. rESCs are an important system for understanding stem cell and tissue biology and for creating transgenic or knockout rats, which are used as in vivo disease models, through homologous recombination. Recent applications of rESCs include the identification of factors that maintain pluripotency, research into human genetic diseases, the identification of new differentiation factors and cancer biology.