microtubule cytoskeleton in developing cysts of the green alga Acetabularia: involvement in cell wall differentiation

Cysts of the green alga Acetabularia develop a unique lid structure to enable the release of gametes. This lid is separated from the rest of the thick cellulose cell wall by a circular fault line formed within the fibrillar texture of the wall. By immunofluorescence microscopy, we show that, prior to the first division of the single cyst nucleus, the radially symmetrical, perinuclear microtubule system which is a remnant carried over from previous developmental stages of cyst morphogenesis transforms into a circular microtubule band (CMB) around the nucleus.