A theca (plural thecae) refers to any case, covering, or sheath.

In botany, the theca of an angiosperm is half of the anther. An anther and its filament form together a typical (or filantherous) stamen, part of the male floral organ.

Each anther is bilocular, i.e. it consists of two thecae. Each theca contains two pollen sacs (the male sporangium with the microspores).

The tissue between the locules and the cells is called the connective and the parenchyma. Both pollen sacs are separated by the stomium. When the anther is dehiscing, it opens at the stomium.

The outer cells of the theca form the epidermis. Below the epidermis, the somatic cells form the tapetum. These support the development of microspores into mature pollen grains. However, little is known about the underlying genetic mechanisms, which play a role in male sporo- and gametogenesis.

The thecal arrangement of a typical stamen can be as follows :
* divergent : both thecae in line, and forming an acute angle with the filament
* transverse (or explanate) : both thecae exactly in line, at right angles with the filament
* oblique: the thecae fixed to each other in an oblique way
* parallel : the thecae fixed to each other in a parallel wayIn biology, the theca of follicle can also refer to the site of androgen production in females.

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  • Theca — The ca, n.; pl. {Thec[ae]}. [L., fr. Gr. ? a case to put anything in. See {Tick} a cover.] 1. A sheath; a case; as, the theca, or cell, of an anther; the theca, or spore case, of a fungus; the theca of the spinal cord. [1913 Webster] 2. (Zo[… …   The Collaborative International Dictionary of English

  • THECA — in Vita Eligii Episcopi Noviom. Multis Sanctorum ex auro, argento atque gemmis fabricavit thecas sive tumbas, capsa est SS. reliquiis instructa. Ex Graeco θήκη, quod inter alia loculum, in quo defuncti corpus efferebatur, inprimis notavit. Eâdem… …   Hofmann J. Lexicon universale

  • Theca — (v. gr.), 1) Behältniß, worin man etwas aufbewahren kann, z.B. Kiste, Kasten, Sarg; 2) Scheide, in welche man die Schreibgriffel steckte; 3) (Beerenkapsel), der nach abgefallener Haube u. Deckel auf dem Fruchtstiel sitzen bleibende, einfächerige …   Pierer's Universal-Lexikon

  • Theca — (lat., »Büchse«), die Frucht der Moose; das Antherenfach der Staubgefäße; bei Schlauchpilzen der Sporenschlauch …   Meyers Großes Konversations-Lexikon

  • thecă — v. tecă. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • theca — [thē′kə] n. pl. thecae [thē′sē] [ModL < L < Gr thēkē, a case < IE * dhēkā < base * dhē , to place, put > DO1, L facere] 1. Bot. a spore case, sac, or capsule 2. Zool. Anat. any sheath or sac enclosing an organ or a whole organism,… …   English World dictionary

  • theca — A sheath or capsule. [G. theke, a box] t. cordis SYN: pericardium. t. externa SYN: tunica externa thecae folliculi. t. folliculi the wall of a vesicular ovarian follicle. SEE ALSO: tunica externa, tunica interna thecae …   Medical dictionary

  • Theca — The̱ca [von gr. ϑηϰη = Abstellplatz; Behältnis; Kasten] w; , ...cae: bindegewebige Hülle eines Organs; eindeutschend auch: Theka (Anat.). The̱ca ex|tẹrna: äußere, faserige Schicht der Theca folliculi. The̲ca ex|te̱rna (the̲cae folli̱culi): neue… …   Das Wörterbuch medizinischer Fachausdrücke

  • Theca — Als Theca (Plural: Thecae, auch Theke) werden bezeichnet: In der Zoologie Teile von Wohnröhren sessil lebender Tiere, etwa: die aus paarig aufeinandergestapelten Gerüsthalbringen aus Protein aufgebauten Wohnröhren der Graptolithen die kalkigen… …   Deutsch Wikipedia

  • theca — thecal, adj. /thee keuh/, n., pl. thecae / see/. 1. a case or receptacle. 2. Bot., Mycol. a. a sac, cell, or capsule. b. a sporangium. 3. Anat., Zool. a case or sheath enclosing an organ, structure, etc., as the horny covering of an insect pupa.… …   Universalium

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