Fertilised eggs get microscopic bar codes

Short Sharp Science: Fertilised eggs get microscopic bar codes: Researchers have come up with an ingenious solution for keeping track of embryos and egg cells during in vitro fertilisation procedures: microscopic bar codes. Mouse eggs were tagged by injecting microscopic silicon bar codes into their perivitelline space, the gap between the cell membrane and an outer membrane called the zona pellucida, which binds sperm cells during fertilisation. The bar codes, which carry unique binary identification numbers, are biologically inert: they do not affect the rate of embryo development and are shed before the embryos implant into the wall of the uterus. The technique aims to simplify individual embryo identification, streamlining in vitro fertilisation and embryo transfer procedures.