Human Y chromosome (IMAGE) NIH/National Human Genome Research Institute Caption The Y chromosome is the last of the 24 human chromosomes to be completely sequenced. Credit Darryl Leja, National Human Genome Research Institute (NHGRI) Usage Restrictions Credit must be given to the creator. License CC BY 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.