Making the invisible visible – a pictorial tribute to Lennart Nilsson

Lennart Nilsson (1922-2017), a Swedish master photographer, revolutionised biomedical visualisation by merging artistic vision with scientific precision. His collaboration with the Karolinska Institute in the 1950s led to the first detailed images of human embryonic development, later published in Life magazine and in the book A Child is Born (1965). These works transformed humanity's understanding of the origins of life and established a new standard in scientific imaging. Building on Nilsson's legacy, this pictorial tribute explores the principle of "form follows function" in biological systems, emphasising how structure reflects physiological purpose. Using advanced imaging techniques such as microvascular corrosion casting and hierarchical phase-contrast tomography (HiP-CT), we visualise organ architecture at cellular resolution. Current initiatives, including the Human Organ Atlas Hub and the HIMALAYA project, integrate imaging, molecular and clinical data to deepen our understanding of human anatomy and disease - continuing Nilsson's vision of revealing life's hidden structures through the fusion of art and science.