1622

Army surgeon Gaspare Aselli, then in Milan, while dissecting a dog recently fed and killed, discovered lacteals, i.e., abdominal vessels covering the mesentery and intestines and which, on puncture, containing a milky white substance. Repeated animal experiments showed the vessels only appeared after recent feeding, and Aselli concluded “that the vessels were indeed lacteals, vessels that carry digested food (chyle) from the intestines.” His discovery was set forth in De lactibus, published posthumously in 1627. In 1628, Fabrice de Peiresc confirmed observation of lacteals on dissection of a criminal fed two hours before his execution. It fell to French physician Jean Pecquet in 1651 to “accurately describe the cisterna chili (also called the receptacle of Pecquet) and the thoracic duct along with its valves, where the lymphatic system terminates into the left subclavian vein.” Aselli’s discovery was opposed by William Harvey, who maintained on the basis of erroneous Galenic assumptions that mesenteric veins transport chyle to the liver.  (Park &I Riva; Suy et al., I, 165-66; Suy et al., II, 325-27; Natale, et al., 421-22). Indeed, “The anatomy and the physiology of the digestive system according to Galen were indeed supposed to be the only real truth in the first half of the seventeenth century (Suy et al., II, 330)