MARGINAL BANDS OF LOBSTER BLOOD CELLS: DISAPPEARANCE ASSOCIATED WITH CHANGES IN CELL MORPHOLOGY

¹ Department of Biological Sciences, Hunter College, 695 Park Ave., New York, NY 10021, and The Marine Biological Laboratory, Woods Hole, MA 02543.

Blood cells of the lobster Homarus americanus were examined for the presence of marginal bands of microtubules (MBs). Nearly all of the cells were highly flattened and elliptical immediately after removal from the animals, and they contained cytoplasmic granules. Rapid cell lysis with Triton X-100 under microtubule-stabilizing conditions produced granule-free "clots" in which almost every nucleus had an associated MB. Thin sections of intact, oriented cells revealed MBs of 50-60 microtubules in classical location in the plane of cell flattening, close to (but not touching) the plasma membrane. Cells rapidly lost native morphology as they spread on glass substrata. The fate of the MB during spreading was followed in lysed cell "cytoskeletons" under phase contrast and by means of indirect anti-tubulin immunofluorescence. MBs initially appeared twisted, then splayed apart, and finally disappeared completely after cell spreading for 20 min. These observations and previous literature support identification of the MB-containing cells as the clotting cells of Homarus, in which the in vitro behavior may reflect a self-destructive in vivo mechanism. Their similarity to clotting cells of other species is discussed.

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