Marginal bands in nucleated erythrocytes

Marginal bands from erythrocytes of several non‐mammalian vertebrates were studied by light and electron microscopy. Cells were observed in thin sections after various fixing procedures and in wholemount preparations. Isolated marginal bands were prepared by air drying and freeze drying. The marginal bands are composed of tubular elements which vary in diameter from 200 Å to 500 Å, depending on the preparation method. It is suggested that these tubules are part of a general class of microtubules, and that the real diameters of microtubules are approximately twice those observed in fixed and sectioned material.