The fine structure of the thrombocyte in the dogfish (Mustelus canis) with special reference to microtubule orientation

The cytoplasm of the dogfish ( Mustelus canis ) thrombocyte was found to contain microtubules. The tubules which measured 230 Å in diameter appeared singly and in groups. They were found in all parts of the cytoplasm but usually close to the perinuclear area. Similar arrangements of tubules were observed in eosinophils and hemoblasts, but not in the mature, smaller lymphocytes. The orientations of the perinuclear bundles frequently reflected the shape of the nuclei, appearing in furrows, indentations, and between lobes.