ON THE DEVELOPMENT OF THE ISLETS OF LANGERHANS

Studies of pancreatic development have suggested that the islet cells develop through multihormonal stages. Abundant data have confirmed tha t multihormonal cells are common during pancreatic development. A numb er of transcription factors and homeotic proteins have also been found to be important to pancreatic and islet cell development. While one o f these factors (Isl1) is important for the development of the dorsal pancreatic bud and mesenchyme, another factor (Pdx1) is needed for gro wth and branching of both pancreatic buds. Studies of the expression p atterns of pancreatic hormones and transcription factors and other mar ker proteins seem at present to be most compatible with the view that early glucagon and glucagon + insulin expressing cells are precursors to the glucagon cells of the islets while mature B cells arise through differentiation from glucagon-negative precursor cells. Recent data a lso point to possibilities of local paracrine interactions between isl et cell types and the parenchymal tissue during development. (C) 1998 Wiley-Liss, Inc.