endothecium


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Related to endothecium: amphithecium, stomium, tapetum

endothecium

[‚en·də′thē·shē·əm]
(botany)
The middle of three layers that make up an immature anther; becomes the inner layer of a mature anther.
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The middle layers had a common histogenetic origin with the endothecium.
The walls of the endothecium thickened after the microspores formed (Fig.
However, the classic model of anther development involving three 'germ layers' that give rise to specific cell lineages (LI to epidermis, L2 to endothecium, middle layers, outer tapetum and archesporial cells, and L3 to connective and inner tapetum) and the well accepted dual origin of tapetum in angiosperms, has been challenged.
During meiosis, the cells of endothecium layer are tangentially elongated and have spiral thickenings which are made of lignin.
Development of anther wall follows the dicotyledonous type, which is composed of an epidermal layer, an endothecium layer, one middle layer and tapetum.
The species of Enkianthus differ from other Ericaceae in having anthers with fibrous endothecium, monadinous pollen without viscin threads, and seeds with vascular bundles in the raphe, but these features may represent symplesiomorphies, and as such they are not diagnostic of the genus.
The stamens are twice the number of the corolla-lobes and have anthers that are smooth to distinctly papillose, opening with longitudinal slits by means of a fibrous endothecium.
From the cross section we see that the anther wall consists of five layers from outer to inner: an epidermis, endothecium, two rows of middle layer and a layer of tapetum (Fig.
THE LOCULE SURROUNDING EXTERNAL LAYERS: EPIDERMIS, ENDOTHECIUM, AND MIDDLE LAYERS
In this case, the first wave of starch degradation can be correlated with parallel anther growth, formation of endothecium thickenings, and tapetum development, whereas the second may be due to the arrest of anther growth and a subsequent surplus of soluble sugars from the filament (Clement et a l.
On maturation of the anther, the sporangial wall consists of the epidermis and the endothecium, whereas the middle layers and tapetum disintegrate.
He removed the pollen grains and pollenkitt from a dehisced anther and then detached the tapetal membranes on the inner tangential endothecium wall together with the orbicules.