CORTICAL MICROTUBULE ORGANIZATION AND INTERNODAL CELL MATURATION IN CHARA-CORALLINA

The arrangement of cortical microtubules, as documented by immunofluor escence and immunogold-silver enhancement, changes during the growth a nd maturation of giant internodal cells of Chara corallina, a process taking approximately 45 days. Transverse microtubules are found throug hout growth along with a subset of distinctly non-transverse microtubu les. During the second half of the growing period, when relative growt h rates are diminishing, these nontransverse microtubules become more abundant but a few days prior to growth cessation, they are mostly abs ent. At about the time of growth cessation the microtubules, while ret aining their locally parallel alignment, begin to show increasing devi ation from the transverse axis. Eventually, a mosaic of locally parall el yet variably oriented fields of microtubules forms. Many days after growth stops, microtubules become shorter and less numerous and lose parallel alignment, leading to the formation of a random MT pattern.