Fig. 6.

Comparison between the ultrastructures of Drosophila, PtK₁, and HeLa cell kinetochores in the absence and presence of MTs. The side-by-side comparison with vertebrate kinetochores indicates that the electron-dense outer layer observed in unbound Drosophila kinetochores (brackets and arrowheads), although it is less distinct, clearly corresponds to the classical outer plate in unbound vertebrate kinetochores. The presence of MTs distorts the kinetochore structure in all three species. Nevertheless, the putative outer plate (arrowheads) is still visible in favourable views of Drosophila kinetochores. Scale bar=200 nm