Cytoplasmic fragmentation in human embryos in vitro: implications and the relevance of fragment removal

During the early days of human embryo culture in vitro, Edwards1 observed a phenomenon he described as “cell division without nuclear division.” This was noted in both developing and arrested embryos and, reminiscent of a similar occurrence in somatic cells, was later termed fragmentation. That observation still holds true: partial or total loss of cellular integrity can affect a large percentage (34521/51 599) of cleavage stage embryos in vitro (EggCyte™ database, Art Institute of New York and New Jersey, 1995-2000).