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Sieve tube element. Sieve elements are specialized cells that are important for the function of phloem, which is a highly organized tissue that transports organic compounds made during photosynthesis. Sieve elements are the major conducting cells in phloem. Conducting cells aid in transport of molecules especially for long-distance signaling.
Platelets or thrombocytes (from Ancient Greek θρόμβος (thrómbos) 'clot' and κύτος (kútos) 'cell') are a blood component whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby initiating a blood clot. [1] Platelets have no cell nucleus; they are fragments of ...
The terminal portion of the optic nerve and its entrance into the eyeball, in horizontal section. The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form the optic ...
Over the following 18 hours, both the inner and outer layers begin to flex inward at sharp angles, beginning the formation of a C-shaped edge (Phase 3). The final 18 hours involve continuing this apically convex invagination to form the optic cup [3] [4]. At this point, morphologies such as columnar epithelial cells, pseudo-stratified cells ...
Vascular endothelial growth factor (VEGF, / vɛdʒˈɛf /), originally known as vascular permeability factor (VPF), [1] is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors, the platelet-derived growth factor family of cystine-knot growth factors.
Lens (vertebrate anatomy) Lens of eye changing shape to focus near and far. Schematic diagram of the human eye. The lens, or crystalline lens, is a transparent biconvex structure in most land vertebrate eyes. Relatively long, thin fiber cells make up the majority of the lens. These cells vary in architecture and are arranged in concentric ...
Nitric oxide (nitrogen monoxide) is a molecule and chemical compound with chemical formula of N O. In mammals including humans, nitric oxide is a signaling molecule involved in several physiological and pathological processes. [1] It is a powerful vasodilator with a half-life of a few seconds in the blood.
A vessel element or vessel member (also called a xylem vessel) [1] is one of the cell types found in xylem, the water conducting tissue of plants. Vessel elements are found in most angiosperms (flowering plants) but absent in some gymnosperms such as conifers. Vessel elements are the main feature distinguishing the "hardwood" of angiosperms ...