Implantation during Day 6 of Development (IMAGE) University of Warwick Caption This is an expression of trypsinogen activating enterokinase (green) in an implantation competent hatching human blastocyst on day six of development. Credit Scarlet Salter & Anatoly Shmygol Usage Restrictions Only with credit 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.