Figure 5.

(A) A sketch of ox's heart by Leonardo da Vinci. Many of da Vinci's heart drawings were made from studies of the organs of pigs and oxen. Only later in his life that he had access to human organs. The script was written in the famous mirror-image da Vinci's style. The sketch is one of Windsor Folios, part of the Royal Collection, Windsor, UK. (B) From the same collection, a sketch of human's heart by Leonardo, where the interventricular pores are clearly depicted according to Galen's anatomy.