Marcello Malpighi

Importance to Hirudotherapy

Marcello Malpighi is the founding figure of microscopic anatomy and the investigator whose 1661 discovery of pulmonary capillaries completed William Harvey's circulation doctrine. His significance for the long-term scientific understanding of leech therapy lies in the way his microscopic anatomical work provided the foundation on which the local microvascular effects of leech-secreted bioactive compounds could ultimately be studied and understood. Where Harvey had demonstrated that the blood circulates in a closed system but had been unable to identify the connection between the arterial and venous limbs at the periphery, Malpighi's microscopic examination of the frog lung revealed the capillary network through which blood passes from artery to vein. Malpighi's broader microscopic work — on the lung, kidney, liver, skin, and various invertebrate organisms — established microscopic anatomy as a distinct scientific discipline and provided the methodological framework within which later investigators could study the structure of leeches themselves and the microvascular effects of their secretions on the host organism. The microscopic anatomical tradition that Malpighi founded led, two centuries later, to the histological and pharmacological techniques used by Haycraft in his Edinburgh laboratory to isolate hirudin from leech salivary glands and to characterize its effects on the coagulation of blood. The American Society of Hirudotherapy regards Malpighi as an indispensable foundation figure in the chain of scientific developments from Harvey's circulation doctrine to the modern molecular pharmacology of leech bioactive proteins. The detailed microscopic understanding of capillary structure, microvascular flow, and host-tissue response that underwrites the modern clinical use of medicinal leeches in microsurgical flap salvage descends directly from the seventeenth-century Italian microscopic tradition of which Malpighi is the founding figure.