Myron C. Ledbetter

Morphology of Microtubules of Plant Cell

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.

The Plant Cell: Aspects of Its Form and Function

Publisher Summary This chapter discusses the plant cell and focuses on the aspects of its form and function. The cellular components characteristically observed in plant cells include mitochondria, proplastids, dictyosomes, nuclei, ribosomes, endoplasmic reticulum, and cell membranes. The mitochondria are ovoid to round organelles, although they also can be very irregular in shape as often seen in animal cells. The nuclei of plant cells are quite variable in size and shape, but most are typically spherical. The ribosomes of plants are small particles scattered in groups or clusters throughout the cytoplasm. Despite the universal acceptance of the physiological importance of the plasmodesmata, there are relatively few well-established evidences of their role. Their chief functions are related to the conduction of metabolites from one region of the plant to another and the movement of hormonal stimuli important in growth regulation. In nonvascular tissues such as those found in many mosses, liverworts, and fern gametophytes and in vascularized plants within regions comparatively isolated from phloem sieve cells, it seems very probable that the plasmodesmata are of particular importance.