Galleries of spindle MT plus ends. (A) 4-nm slices that contain the ends of four algal metaphase KMTs. In all panels of this figure, arrows indicate flaring PFs and arrowheads demark fibrils that run from the PFs to nearby chromatin. (A′) Analogous images of non-KMTs. (B) 4-nm slices of four metaphase KMTs from C. elegans. (B′) Analogous images of non-MTs. (C) 4-nm slices from the plus ends of KMTs from S. cerevisiae. Here, no chromatin is evident, but there are small circular densities not far from each MT end. (C′) Budding yeast non-KMTs. Leftmost is the plus end of an “astral” MT that projected from the spindle pole body into the cytoplasm. The center and right images are from ipMTs in the anaphase interzone. (D and D′) 4-nm slices of KMTs and non-KMTs from fission yeast. The electron densities near the tips of the KMTs in D are suggestive of chromatin, but a well-formed chromosome is not seen. The non-KMTs of D′ are pole-distal ends of MTs that diverged widely from the spindle axis (two leftmost images) and from MTs that ended in the anaphase interzone (two rightmost images). Bars: (A) 100 nm; (A′) 75 nm; (B) 100 nm; (B′) 50 nm; (C and C′) 50 nm; (D and D′) 50 nm.