Key points are not available for this paper at this time.
The microtubules present in the cortices of plant cells are found to have a wall made up of slender filamentous subunits, probably 13 in number, which have a center-to-center spacing of about 45 angstrom units. Thus the micromorphology of these tubules is similar to that reported for the 9 + 2 fibrils of rat sperm flagella. This structure can be used to account for a primary function of motion attributable to the microtubules.
Ledbetter et al. (1964) studied this question.