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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Theca and granulosa cells were also defined as invasive cells by Guraya (1986), Miranda et al.
The enzyme type 17[beta]-hydroxysteroid dehydrogenase type 5 (HSD17B5) is instrumental in converting androstenedione to testosterone in theca cells and adrenal glands [137].
Very few IL-16-expressing cells are seen in the stroma and theca layer of the stromal follicle.
Terakawa, "Hepatocyte growth factor and stem cell factor involvement in paracrine interplays of theca and granulosa cells in the human ovary," Fertility and Sterility, vol.
Moreover, both theca cellular hyperproliferation and follicular atresia induced granulosa cell inactivation in hyperandrogenism (such as PCOS) mediate follicular abnormal development.
Hyperreactio luteinalis is a rare disease characterized by marked cvstic enlargement of the ovary due to multiple benign theca lutein cysts.
In vivo treatment with GDF-9 stimulates primordial and primary follicle progression and theca cell marker CYP17 in ovaries of immature rats.
Overexpression of a DENND1A isoform produces a polycystic ovary syndrome theca phenotype.
The high level of LH stimulates the cells of the stroma and theca to produce androgens, mainly androstenedione and testosterone.