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Within the 20-year timespan, many scientists have actively contributed to examining and reevaluating Hager's acid-growth hypothesis. Despite the accumulation of observations that evidently identify the final target of the auxin-induced action to be H +-ATPase, which excretes H + protons to the apoplast and take in K + ions through its rectifying K + channel in the following years, the ...
Like seedlings, adult plant shade avoidance involves several mechanisms acting together. Petiole elongation is both a result of cell expansion and cell division, though not at the same stage in petiole and leaf formation. In newly growing leaves, cell division is the primary factor, while fully formed leaves and petioles rely on cell expansion ...
Expansins characteristically cause wall stress relaxation and irreversible wall extension (). [15] This process is essential for cell enlargement. Expansins are also expressed in ripening fruit where they function in fruit softening, [16] and in grass pollen, [7] where they loosen stigmatic cell walls and aid pollen tube penetration of the stigmain germinating seeds for cell wall disassembly ...
Aerenchyma in stem cross section of a typical wetland plant. Aerenchyma or aeriferous parenchyma [1] or lacunae, is a modification of the parenchyma to form a spongy tissue that creates spaces or air channels in the leaves, stems and roots of some plants, which allows exchange of gases between the shoot and the root. [2]
The frenulum is the highly vascularized elastic band of tissue located on the underside of the glans that connects the foreskin to the head of the penis. The frenulum is supple enough to allow the retraction of the foreskin over the glans and pull it back when the erection is gone. [18] In flaccid state, it tightens to narrow the foreskin ...
The procedure usually involves the removal of the frenulum or the creation of an incision in the frenulum that is then stretched to lengthen it and stitched closed. The incision can be z-shaped, y-shaped or a single horizontal cut. Once healed, the procedure effectively elongates the frenulum, allowing normal function.
Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
This thickening is secondary growth and is needed to give mechanical support and stability to the plant. [4] The functions of a plant's growing tips – its apical (or primary) meristems – include: lengthening through cell division and elongation; organising the development of leaves along the stem; creating platforms for the eventual ...