Liver Bud is a medical term used to describe the early stages of liver development. The liver is a vital organ that plays a critical role in metabolism, detoxification, and digestion. The liver bud begins to form during the third week of embryonic development. It is initially composed of two small lobes that grow and fuse together over the next few weeks.
The liver bud starts out as a simple mass of cells that gradually differentiates into hepatocytes, bile duct cells, and stellate cells. These cell types give rise to the various functional regions of the mature liver. Hepatocytes make up the bulk of the liver tissue and are responsible for most of its functions. Bile duct cells line the bile ducts and secrete bile acids needed for fat absorption and cholesterol metabolism. Stellate cells are found in the connective tissue around blood vessels and help to maintain vascular stability.
During fetal development, the liver grows rapidly and by birth it typically weighs about 1% of body weight. After birth, growth slows but continues at a steady rate until adulthood when it reaches its full size (about 3% of body weight). The vast majority of hepatocytes are generated during fetal life; however, they can also be produced throughout adulthood in response to injury or disease (e.g., hepatitis C).