When did Andreas Vesalius discover his theory?

Andreas Vesalius, a 16th-century Flemish anatomist, is best known for his groundbreaking work in human anatomy, which he published in "De humani corporis fabrica" in 1543. This work challenged the prevailing Galenic theories and laid the foundation for modern anatomy through detailed observations and dissections. His meticulous studies marked a significant shift in the understanding of human anatomy during the Renaissance.