Malpighi and the discovery of capillaries.

Leonardo da Vinci clearly observed and described capillaries. Using the microscope, Marcello Malpighi examined the brain and major organs to demonstrate their finer anatomical features. This led to his discovery in 1661, of capillaries that proved fundamental to our understanding of the vascular system in the brain and cord. He hypothesized that capillaries were the connection between arteries and veins that allowed blood to flow back to the heart in the circulation of the blood, as first asserted by William Harvey.