Theca

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theca

[′thē·kə]
(anatomy)
The sheath of dura mater which covers the spinal cord.
(botany)
A moss capsule.
A pollen sac.
(histology)
The layer of stroma surrounding a Graafian follicle.
(invertebrate zoology)
The test of a testate protozoan or a rotifer.

Theca

 

various types of sheath in animals and plants:

(1) A cell wall in certain amoebae (thecamoebae).

(2) A chitinoid membrane in hydroid polyps; hence the division into the suborders Thecaphora and Athecata.

(3) The connective tissue surrounding ovarian follicles in vertebrates (theca folliculi).

(4) A tooth socket in the jawbone of mammals and crocodiles.

(5) A capsule for spores in mosses.

(6) The valve of a silicified test; in diatoms, the upper half is the epitheca and the lower half, the hypotheca.

(7) The pollen sac of an anther in angiosperms.

References in periodicals archive ?
The members of the Gothograptus lineage are characterized by tubaria tapering distally, most of them by a well-developed appendix, and singular genicular hoods as well as characteristic features of the proximal end, and thecae (e.
5 mm longo; thecae circa 1 mm longae, appendicibus ovatis circa 0.
Concerning the content, the reader finds a thorough study of the late Phoenician tradition of inhumating the dead in thecae and anthropoid sarcophagi.
similis 5b R1, R2 and R3 equally or subequally distanced, a list is present behind R3 6a Cells medium-sized, 45-60 [micron]m long, with areolated thecae, LSL having the same width in its anterior and posterior parts (6) Dinophysis ovum 6b Cells small, 28-38 [micron]m long, with smooth thecae, LSL increasing in width from R1 backward (7) Dinophysis cf.
One petal from the inner whorl remains free while all other perianth members fuse to form a floral tube that, together with the exposed thecae (in staminate flowers), forms the floral display.
Flores hermaphroditi circa 10 (5-12); corollae tubulosae 5-denticulatae; filamenta antherarum in parte superiore distincta, thecae oblongoovatae base obtusae; styli glabri appendicibus elongati oblongi ad apicem triangulares.
5 mm latae, thecae aequales, divaricatae vel leviter deflexae, totae dehiscentes; capsula turbinata 4.
In many species, the connective between the two thecae forms an apiculus or connective crest (Haines & Lye, 1983) (Fig.
5 mm altae anguste infundibulares extus piloso-glanduliferae intus glabrae 5 lobatae, lobis triangularibus; filamenta antherarum in parte superiore distincta, thecae 1.
The anthers are typically caudate, with the pollen-bearing anther thecae extending below the attachment point of the filament (i.