Fine fibrils in the basilar membranes of mouse and guinea-pig cochleae
were examined by transmission electron microscopy. The fibrils were 1
0 nm in diameter and ran straight without branching. The fibrils appea
red as two parallel lines in longitudinal sections, and round or polyg
onal in cross-sections, displaying tubular structures with a lumen. Th
ey were similar in ultrastructural details to the elastin-associated a
nd elastin-independent microfibrils of Low (1962) in the subcutaneous
tissue. It is concluded that the fibrils in the basilar membrane are t
he microfibrils.