FIGURE 10.

Ribbon→filament transitions immunolabeled with anti-tektin antibodies. The bare connecting or extending filaments are labeled by all three of the specific anti-tektin antibody/gold particles (marked by arrowheads), indicating that the single filament is composed of tektins A, B, and C; the statistics of the gold labeling are given in the text. a, nonspecific background labeling by gold is low (one of the few exceptions is labeled by an asterisk). Rarely do these antibodies/gold particles label Ribbons, indicating that the epitopes of tektins in the intact Ribbon are inaccessible to the antibodies. a–d, anti-tektin-A labeling of Ribbon→filament transitions. a, S. purpuratus Ribbons; b–d, L. pictus Ribbons. e–h, anti-tektin-B labeling of S. purpuratus Ribbon→filament transitions. i–p, anti-tektin-C labeling of L. pictus Ribbon→filament transitions. Scale bars, a, i, and j, 200 nm; b–h and k–p, 100 nm.