Fig. 7. Immunolocalization of Nowa protein in the early growth phase of nematocyst morphogenesis. (A,B) Confocal microscopy of mAb H22 (green) and minicollagen antibody (red) in early stages of nematocyte differentiation. Nuclei are stained with DAPI (blue). (A) Early and late stages of capsule development in an optical section. (A') Enlargment of one of the early stage nematocytes with nematocyst primordium. Staining of mAb H22 is restricted to the wall and tubular-vesicular structure at the apex (arrow), while minicollagen is detected in the ER and matrix of the capsule, as depicted in the drawing in B. (C) EM-section of nematocyte with nematocyst primordium. Immunogold mAb H22 labeling is found in the capsule matrix (cm), the outer layer of the capsule wall (cw), the Golgi apparatus (g), as indicated by an arrow, and membrane compartments associated with the primordium but not in the ER (n, nucleus). (D,D') Formation of the inner wall layer by minicollagen. Minicollagen is no longer found in the matrix of the capsule but forms the inner wall (iw) adjacent to the mAb-H22-positive outer wall (ow). (E) Isorhizatype nematocyst with tubular-vesicular structures at the growing apex (arrow) in an optical section. Bars, 5 µm (A,A',B,D); 1 µm (C).