(a) Living erythrocytes of the smooth dogfish, phase contrast; long axis of ellipsoid (bar) = 18 µm. (b) Cytoskeleton (extracted with Triton X-100 ) as seen in phase contrast; arrow indicates marginal band of microtubules. N = nucleus; bar = 5µm. (c) Cytoskeleton whole mount (extracted with Triton X-100 ); uranyl acetate staining, transmission electron microscopy. Marginal band (MB), membrane skeleton (MS), and nucleus (N) are visible. Bar = 2µm.