Figure 1.

Axon guidance molecules are involved in islet morphogenesis and cell-cell contact. (A) Islet development begins as proendocrine cells delaminate from branching ducts and migrate across the pancreatic mesenchyme. Eph receptors are involved in epithelial cell branching. Semaphorins expressed by peripheral mesenchyme draw neuropilin receptor-expressing proendocrine cells away from the ducts. Netrins, neogenin, and integrins are also known to regulate epithelial cell migration. (B) As endocrine cells aggregate into islets, Slit from pancreatic mesenchyme interacts with Robo on β cells to direct cell type sorting and establish appropriate islet architecture.