Cortical Microtubule Organization and Internodal Cell Maturation in Chara corallina

Summary The arrangement of cortical microtubules, as documented by immunofluorescence and immunogold‐silver enhancement, changes during the growth and maturation of giant internodal cells of Chara corallina , a process taking approximately 45 days. Transverse microtubules are found throughout growth along with a subset of distinctly non‐transverse microtubules. During the second half of the growing period, when relative growth rates are diminishing, these non‐transverse microtubules become more abundant but a few days prior to growth cessation, they are mostly absent. At about the time of growth cessation the microtubules, while retaining their locally parallel alignment, begin to show increasing deviation from the transverse axis. Eventually, a mosaic of locally parallel 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.