Fig. 4

Electron microscopic immunolabeling of anti-radixin activity in the chicken's cochlea. (A) A high-magnification electron micrograph depicts the base of a typical stereocilium bearing two ImmunoGold particles, one on the lower shaft and the other on the stereociliary taper. Additional particles adorn the surfaces of two neighboring stereocilia. (B) A lower-magnification micrograph displays the entire stereocilium whose base is depicted in A; the rectangular box indicates the enlarged region. All immunolabeling in this instance is confined to the lowest 0.6 μm of the stereocilium. (C) Each bin of the histogram depicts the average number of particles per hair bundle encountered in 0.2-μm intervals measured axially along the stereocilia from their basal insertions. A total of 227 gold particles was measured from stereocilia in 22 hair bundles ranging in height from 3.0 to 4.2 μm (3.6 ± 0.3 μm, mean ± SD). All stereocilia were oriented within 15° of the plane of section, so the measurement error owing to obliquity was negligible. Because no attempt was made to compensate for shrinkage during specimen preparation, however, the distance measurements are probably underestimates. (D) An electron micrograph of the apical surface of a supporting cell, which is attached to each of the neighboring hair cells by a junctional complex comprising a tight junction (zonula occludens) and an intermediate junction (zonula adherens). Three ImmunoGold particles occur on one microvillus. (Scale bars in A and D, 0.2 μm; the ordinate of the histogram in C calibrates the aligned micrograph in B.)