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The filaments may be fused and the anthers free, or the filaments free and the anthers fused. Rather than there being two locules, one locule of a stamen may fail to develop, or alternatively the two locules may merge late in development to give a single locule. [ 13 ]
Valvular – anthers opening through valves or small flaps; e.g. Berberis. Versatile – anthers pivoting freely on the filament. Pollen – Stamen – Anther – the distal end of the stamen where pollen is produced, normally composed of two parts called anther-sacs and pollen-sacs . Filament – the stalk of a stamen.
The filaments are fused to the corolla, while the anthers are generally connate (syngenesious anthers), thus forming a sort of tube around the style (theca). They commonly have basal and/or apical appendages.
Most anthers are formed on the apex of a filament. An anther and its filament together form a typical (or filantherous) stamen, part of the male floral organ. The typical anther is bilocular, i.e. it consists of two thecae. Each theca contains two microsporangia, also known as pollen sacs.
Connation in plants is the developmental fusion of organs of the same type, for example, petals to one another to form a tubular corolla. [1] [2] This is in contrast to adnation, the fusion of dissimilar organs. Such organs are described as connate or adnate, respectively.
Floral formulae are one of the two ways of describing flower structure developed during the 19th century, the other being floral diagrams. [2] The format of floral formulae differs according to the tastes of particular authors and periods, yet they tend to convey the same information. [1] A floral formula is often used along with a floral diagram.
Two main tapetum types are recognised, secretory (glandular) and periplasmodial (amoeboid). In the secretory type, a layer of tapetal cells remains around the anther locule . In contrast, the tapetal cell walls dissolve in the periplasmodial type, and their protoplasts fuse to form a multinucleate periplasmodium.
This cytokeratin tetramer is considered to be the main building block of the cytokeratin chain. By head-to-tail linking of the cytokeratin tetramers, the protofilaments are originated, which in turn intertwine in pairs to form protofibrils. Four protofibrils give place to one cytokeratin filament. Cytokeratin filaments in the human epithelial cell