The development of William's E Medium by Williams and Gunn was a significant breakthrough in the field of cell culture. This medium was originally designed to support the long-term growth of adult rat liver epithelial cells, providing a stable and reliable environment for these cells to thrive. The medium is supplemented with reduced serum, which allows for the growth and maintenance of these cells without the need for high levels of serum.

One of the key advantages of William's E Medium is its versatility. While it was originally developed for rat liver epithelial cells, it has since been shown to be effective for growing primary hepatocyte cells from a variety of different species. This makes it a valuable tool for researchers working with a wide range of animal models, as well as those studying human liver cells.

In addition to its use in animal models, William's E Medium has also been shown to be effective for growing human derived HepaRG cells. These cells are a valuable tool for studying liver function and disease, as they can be differentiated into hepatocyte-like cells that exhibit many of the properties of primary hepatocytes. The use of William's E Medium in growing HepaRG cells provides a stable and reliable environment for these cells to thrive, allowing researchers to study their behavior and function in a controlled setting.