#cell differentiation

During cereal endosperm development, the triploid primary endosperm nucleus undergoes a series of mitotic divisions without cytokinesis, and the nuclei migrate to the periphery of the central cell, which also contains a large central vacuole (Figure 21.26, see parts A-D). As in the Arabidopsis coenocyte, each of nuclei is surrounded by radially arranged microtubules (see Figure 21.26E). Anticlinal walls form initially between adjacent nuclei, resulting in the tubelike alveolar cells, with the open end pointing toward the central vacuole (see Figure 21.26F). (...) The innermost layer of daughter cells remains alveolar in structure, and continues to divide periclinally until cellularization is complete (see Figure 21.26G and H). The most important source of starchy endosperm cells is the interior cells of the cell files that are present at the completion of endosperm cellularization (see Figure 21.26H).

By delaying the differentiation process, individual leaf primordia can redeploy the gene regulatory networks used by the SAM during leaf initiation to form leaflet primordia, resulting in compound leaf development (Figure 19.7).

Parenchyma can differentiate into ground tissue that has thickened primary walls which can nevertheless continue to elongate (Figure 1.36). Collenchyma in the ribs of celery stalks have very thick, layered walls (see Figure 1.36A-D) and a tasty crunch! The network of laticifers that carry the milky white latex in rubber trees, poppy plants, leaf-lettuce, and dandelions have irregularly thickened primary walls and continue to elongate (see Figure 1.36E and F). (...) The latex particles are contained in differentiated vacuoles; Catharanthus roseus laticifer vacuoles, like the idioblast vacuoles, contain toxic alkaloids (see Figure 1.36F).

Some of these probably fuse together and remodel themselves to form the large central vacuole as the cell matures (see Figure 1.35). (...) Mesophyll cells of the leaf can differentiate into a variety of other cell types under the appropriate environment, and mesophyll is therefore considered a form of parenchyma, a ground tissue with thin primary walls (Figure 1.35A). (...) Young parenchyma cells have multiple small vacuoles, or a reticulated vacuole network (Figure 1.35B), which develops into a large central vacuole. Catharanthus roseus is an interesting case in which both the spongy and palisade mesophyll cells of the plant can differentiate into "special cells", or idioblasts (Figure 1.35C), which contain the important anti-cancer drugs vincristine and vinblastine and are presumably used for defense against herbivory. (...) Calcium oxalate crystals are present in the vacuoles of many species, and may be distributed evenly throughout the leaf or restricted to special cells called idioblasts (see Figure 1.35C).

Fibers develop from parenchyma and form elongated support structures with thickened secondary walls both in ground tissue (see Figure 1.37E) and in vascular tissues (see the phloem fibers in Figure 1.5).

Poor man’s ginseng found to protect against liver damage