Investigations with different ‘antitubulins’ have shown that different cell types in culture response to prolonged treatment with the formation of annulated lamellae. These annulated lamellae are possibly derived from previously accumulated smooth endoplasmic profiles. A hypothetical explanation would be that annulated lamellae (and the nuclear membrane) are sites of tubulin synthesis or microtubular polymerization. Their appearance after induced microtubule disintegration could then be viewed upon as a reactive hyperproduction of such sites.

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