A dicephalic monster embryo ofDrosophila melanogaster

Abstract
A monster embryo with a head on each end developed from an abnormalDrosophila egg produced by a M(1)oSp/Binsn female. The embryo probably represents a longitudinal mirror duplication of head and all 3 thoracic segments. The significance of this type of pattern anomaly for embryonic pattern specification inDrosophila is discussed.