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The endodermis is the boundary between the cortex and the stele. In many seedless plants, such as ferns, the endodermis is a distinct layer of cells immediately outside the vascular cylinder (stele) in roots and shoots. In most seed plants, especially woody types, the endodermis is present in roots but not in stems.
The mycorrhizae of the fungus then uses its extended system to help the plant find the correct area of nutrition, signaling the direction in which the roots should grow. [13] This makes root growth more efficient, preserving energy for other metabolic processes, which in turn benefits the fungus that feeds off those metabolic products.
The initiation of endochondral ossification starts by proliferation and condensation of mesenchymal cells in the area where the bone will eventually be formed. Subsequently, these mesenchymal progenitor cells differentiate into chondroblasts, which actively synthesize cartilage matrix components.
Between the xylem and phloem is a meristem called the vascular cambium. This tissue divides off cells that will become additional xylem and phloem. This growth increases the girth of the plant, rather than its length. As long as the vascular cambium continues to produce new cells, the plant will continue to grow more stout.
During the third week, the paraxial mesoderm is organized into segments. If they appear in the cephalic region and grow with cephalocaudal direction, they are called somitomeres. If they appear in the cephalic region but establish contact with the neural plate, they are known as neuromeres, which later will form the mesenchyme in the head. The ...
Roots are specialized for the uptake of water, nutrients (including ions for proper function). [12] Similar to the endodermis, the exodermis contains very compact cells and is surrounded by a Casparian band, two features which are used to restrict the flow of water to a symplastic fashion (through the cytoplasm) rather than apoplastic fashion which (through the cell wall) flow through passages ...
Cancellous bone or spongy bone, [12] [11] also known as trabecular bone, is the internal tissue of the skeletal bone and is an open cell porous network that follows the material properties of biofoams. [13] [14] Cancellous bone has a higher surface-area-to-volume ratio than cortical bone and it is less dense. This makes it weaker and more flexible.
In a long bone it is a thin disc of hyaline cartilage that is positioned transversely between the epiphysis and metaphysis. In the long bones of humans, the epiphyseal plate disappears by twenty years of age. physis, "the growth part" metaphysis: The region of a long bone lying between the epiphysis and diaphysis.