Figure 3.

(A) A whole platelet mount from a platelet suspension incubated in 1.25% glutaraldehyde phosphate buffer for one hour. The use of aldehyde fixatives, even very briefly, is not recommended and paraformaldehyde treatment gives similar results; the platelet background becomes so dark that only some peripheral granules (δ-arrow) are sometimes visible, but no granules in the platelet center (δ-arrow). (B) dense-granules (red arrows). A simple brief wash in pure water of native platelets on a formvar film is sufficient to obtain electron-translucent cells where the dense-granules are perfectly identifiable. These granules are classically smooth (D) or with filaments (E), but are sometimes observable in restructuring phases as annular forms (C) that split into long extensions (B, bottom left center), possibly also in a division phase (F), where two nodules are visible, which will probably evolve into two well separated dense-granules. The camera in automatic contrast adjustment mode may make the identification of dense-granules doubtful. The quickest solution is to change the magnification rather than the long contrast-brightness-gamma settings; an element looking like a veil at Mag 20 k (G) will be better identifiable at Mag 80 k (H).