Recto: The fetus in the womb. Verso: Notes on reproduction, with sketches of a fetus in utero, etc.

Recto: a large drawing of an embryo within a human uterus with a cow's placenta; a smaller sketch of the same; notes on the subject; illustrative drawings in detail of the placenta and uterus; a diagram demonstrating binocular vision; a note on relief in painting and on mechanics. Verso: a note on light and shade; numerous notes on reproduction; the left side of a fetus with a cord; three drawings of a fetal liver, stomach and umbilical vein; sketches of a chick embryo and membranes. In this drawing the uterus is envisaged as if cut through and opened out, with an ovary in the left margin and the membranes in cross-section. Small sketches below show the uterine membranes unfurling like the petals of a flower. The placenta is shown throughout as multiple, a structure observed in Leonardo’s earlier dissection of a cow (RCIN 919055) – though he seems to have dissected a pregnant woman at some point, he never discovered that the human placenta is single and discoidal. In both this drawing and in RCIN 919101 the fetus is in breech position, with the umbilical cord wrapped around the crossed legs. Leonardo was puzzled that a fetus could fit into the uterus – he states that ‘the length of a child when it is born is usually one braccio [c.60 cm]’ but ‘experience in the dead shows [the uterus] to be a quarter of a braccio in its greatest length’. He repeatedly drew the fetus curled up to occupy the smallest space possible, and in a note on RCIN 919101 he compares the size of the human uterus with that of the cow and the horse, in proportion to their bodies. By the end of his life Leonardo claimed to have performed 30 human dissections. The subjects at this time were usually executed criminals, or, as here, those who had died with no-one to claim their bodies for burial – the ‘child of two years’ mentioned above was presumably a foundling. The apparent ease with which Leonardo obtained permission to perform the dissections suggests that he now had some reputation as an anatomist, or at least that he was on good terms with physicians who facilitated his work. Over the next six years he made great advances in his understanding of human anatomy and physiology, and came close to completing the treatise that he had first envisaged during the 1480s. Text adapted from Leonardo da Vinci: A life in drawing, London, 2018