Fig. 4. Species-specific antibodies recognize epithelial cell surface antigens. (A) H. vulgaris ectodermal epithelial cells are stained with species-specific antiserum visualized with FITC-labelled secondary antibody. Note the strong staining of the apical surface (glycocalix). (B) Uncontrasted ultrathin section through the H. vulgaris (vul)/H. oligactis (oli) graft site. Antibodies coupled with 10 nm gold particles mainly stain glycocalyx of H. vulgaris. (C) Contrasted ultrathin section through the H. vulgaris/H. oligactis graft site (same preparation as in Fig. 5) stained with gold-coupled antibodies. Arrows indicate the heterotypic cellular contact. Scale bars, 0.5 µm.