Whitehead Member Hazel Sive’s research focuses on development of the vertebrate embryo, using frogs and the zebrafish, as model systems. Her lab studies two major topics. The first is development of the extreme anterior (front) of the embryo, a unique and important region. Sive pioneered the study of a simple organ, the mucus-secreting cement gland, as a marker for the extreme anterior in frogs and has used this to define the genetic network by which an organ is positioned. Her lab studies development of another extreme anterior organ, the primary mouth (the first mouth opening), which is essential for normal food ingestion and jaw development. As part of this study, her lab has defined essential signaling factors for primary mouth formation.