Pecquet, Jean (1622–1674)

French anatomist who discovered the thoracic duct, one of two ducts through which fluid collected by the lymphatic system (the network that transports fluids to and from the tissues in the body) empties into the bloodstream.

Pecquet discovered the thoracic duct during animal dissection 1647. The thoracic duct is connected to the lymphatic system, the network of vessels and organs that transports nutrients, oxygen, and white blood cells to the tissues in the body and carries waste matter and carbon dioxide away from the tissues. Lymphatic vessels have very thin walls and the fluid passes into them more easily than back into the blood capillaries. The thoracic duct functions to carry lymph (waste fluid) and chyle (the fluid containing all the nutrients derived from digestion) from the intestinal lymphatic vessels into the cardiovascular system.

Pecquet was born in Dieppe and trained as a doctor first at Paris and then at Montpelier from where he obtained his MD 1652. He reported his findings in Experimenta nova anatomica 1651 and his work prompted a considerable period of research and debate on the structure and function of the lymphatic system in the 17th century.