What Is William’s E Medium? A Clear Guide

William’s E Medium is a nutrient-rich medium best known as the standard choice for culturing liver cells (hepatocytes). It was developed by Gwendolyn Williams for the long-term culture of adult rat liver epithelial cells, and it remains widely used for primary hepatocytes and other specialized cultures. This guide explains what William’s E Medium is, what is in it, and how to use it.

What is William’s E Medium?

William’s E Medium (sometimes written Williams’ Medium E) is a chemically balanced basal medium designed to support demanding primary cells, especially hepatocytes, over extended periods. It was developed as part of a series of media, with formulation E proving the most successful for liver cell culture. Like other basal media, it supplies salts, amino acids, vitamins, and glucose, and it is completed with serum and glutamine before use.

What is William’s E Medium used for?

William’s E Medium is most associated with:

• Primary hepatocytes, where it is a standard culture and maintenance medium
• Liver-related models, including toxicity and metabolism studies
• Other specialized primary cultures that need a rich environment

What is in William’s E Medium?

A typical William’s E formulation contains a broad set of inorganic salts, essential and non-essential amino acids, a rich vitamin profile, glucose, glutathione, and a bicarbonate buffer with phenol red. Because it uses a bicarbonate buffer, it needs a CO2 incubator (usually 5%) to hold the correct pH.

How to supplement and use William’s E Medium

Before use, William’s E Medium is completed with serum (or, for many hepatocyte protocols, defined supplements) and L-glutamine or a stable glutamine dipeptide. For hepatocyte work it is often used with hormones and other additives depending on the protocol. Keep it in a CO2 incubator, store it refrigerated and protected from light, warm it gently before use, and keep the same lot across an experiment for consistency.