Fig. 5. Reformation of an ECM is also observed at the incision site during grafting experiments (A-C) and with morphogenesis during head regeneration (D-F), as monitored by whole-mount immunofluorescence. (A-C) Staining with mAb for hydra laminin (m52). (D-F) Staining for hydra fibrillar collagen (m39). As observed 24 hours after grafting of body segments, the region between the graft halves is the site of ECM biogenesis (region indicated by the arrowheads in A-C). The cut edges of the ECM from each graft appear as two transverse signals at the graft site (only one edge of the ECM is indicated by the arrows in A-C). The region of fusion of the epithelium at the graft site where ECM biogenesis is occurring correlates with deformation in the bilayer. This deformation may be observed as a narrowing or bulging in the body wall at the graft site (indicated by arrowheads in A-C). After decapitation, head regeneration always occurs apical to the original cut edge of the ECM (arrows in D-F), where matrix biogenesis is occurring. Scale bar: 250 µm.
