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A ray appears diagonally, from top left to bottom middle. Medullary rays, also known as vascular rays or pith rays, are cellular structures found in some species of wood. They appear as radial planar structures, perpendicular to the growth rings, which are visible to the naked eye.
In anatomy, a medullary ray (Ferrein's pyramid) is the middle part of a cortical lobule (or renal lobule). Each consists of a group of nephrons in the renal cortex. [1] Their name is potentially misleading, as "medullary" refers to their destination, not their location. They travel perpendicular to the capsule, and extend from the cortex to the ...
Medullary ray may refer to: Medullary ray (anatomy), the middle part of the Cortical lobule; Medullary ray (botany), characteristic radial sheets or ribbons extending ...
Parenchyma forms the "filler" tissue in the soft parts of plants, and is usually present in cortex, pericycle, pith, and medullary rays in primary stem and root. Collenchyma cells have thin primary walls with some areas of secondary thickening. Collenchyma provides extra mechanical and structural support, particularly in regions of new growth.
In addition to the grain, quartersawn wood (particularly oak) will also often display a pattern of medullary rays, seen as subtle wavy ribbon-like patterns across the straight grain. [6] Medullary rays grow in a radial fashion in the living tree, so while flat-sawing would cut across the rays, quarter-sawing puts them on the face of the board.
These products are produced by the cambium and transported to the centre of the stem by cellular structures called medullary rays radiating from the center of the stem [5] and then enter living axial paratracheal parenchyma cells. As the wood ages, the contents of the parenchyma cell burst into the dead vessel through the pit linking the two.
"Ferrein's pyramid": Also known as the medullary ray, which is the center of the renal lobule, and is shaped like a small pyramid. "Ferrein's vasa aberrantia": Aberrant biliary canaliculi that have no connectivity with hepatic lobules.
During secondary growth, cells of medullary rays, in a line (as seen in section; in three dimensions, it is a sheet) between neighbouring vascular bundles, become meristematic and form new interfascicular cambium (between vascular bundles).