Expression of a surface epitope on cells that link branches in the tracheal network of Manduca sexta

A monoclonal antibody (MAb 2F5) to a cell surface epitope labels a small subpopulation of tracheal epithelial cells in each thoracic and abdominal segment of Manduca. These cells (nodes) represent the sites within the tracheal network at which invaginating tracheal tubes join during embryonic establishment of the tracheal network. Tracheal nodes are also the sites at which tracheal cuticle fractures during each molt. Since tracheal cuticle is shed through each spiracle, a tracheal node lies between each pair of contralateral spiracles within a segment (commissural node) and between each pair of adjacent, ipsilateral spiracles (lateral longitudinal node). MAb 2F5 first labels presumptive nodal cells of tracheal epithelium immediately prior to the linking of epithelial tubes from successive and opposite spiracles. One cell at the tip of each invaginating tracheal branch labels with MAb 2F5. The highly localized expression of the cell surface epitope recognized by MAb 2F5 may be instrumental in the orderly coupling of tracheal branches during embryonic development. On the basis of immunolabeling of Western blots and tissues, MAb 2F5 is believed to recognize Manduca fasciclin II, a member of a class of molecules involved in cell adhesion/recognition.