UCLA scientists examining causes of human infertility have found that the cells that create eggs or sperm during the prenatal stage of development are vulnerable to damage, according to new research published today. The study by Amander Clark, of the UCLA Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, was published in the journal Cell. Clark said that the findings advance the understanding of human germ cells, which are responsible for carrying parents’ genes to a child. Abnormalities in the germ cells can cause infertility as well as diseases such as germ cell tumors in young boys and primary ovarian insufficiency in young girls.