(a) Doubly pointed dogfish erythrocytes that appear in cell suspensions incubated in Ringer's solution (~22°C) for ~4 or more hours. Points of one cell are at arrowheads. Phase contrast; bar = 20 µm. (b) Higher magnification view, showing a pointed cytoskeleton obtained from a pointed cell. Several fibers (microtubule bundles) are visible, converging at each pole (arrow). Phase contrast; bar = 5µm. Reproduced with modification from The Journal of Cell Biology, 1982, 93:834, by copyright permission of The Rockefeller University Press.