(IMAGE) Kumamoto University Caption After fertilization, a human embryo implants into the uterus (day 6-12) and gastrulation starts soon afterwards, with the primitive streak emerging at about day 14. Gastrulation allocates cell fates and spatial coordinates to epiblast cells, laying down the foundation of the human body. Credit Dr. Guojun Sheng; Credit for the “Fetus in the womb” sketch by Leonardo Da Vinci: Royal Collection Trust / © Her Majesty Queen Elizabeth II 2021 Usage Restrictions Permission for commercial use of the “Fetus in the womb” sketch by Leonardo Da Vinci must be obtained from the Royal Collection Trust. Any non-commercial use must include the credit line. (https://www.rct.uk/collection/919102/the-fetus-in-the-womb-sketches-and-notes-on-reproduction) License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.