Theca


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Related to Theca: theca folliculi

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 ?
LH and FSH act on theca interna cells and granulosa cells, respectively, to promote estradiol synthesis.
Tumors of the specialized gonadal stroma in human male patients: androblastoma, Sertoli cell tumor, granulosa theca cell tumor of the testis, and gonadal stromal tumor.
Taxonomic note: Preliminary observations of the theca with light microscopy led to recognition of this dinoflagellate as G.
Formation of the CL is initiated by a series of morphologic and biochemical changes in cells of the theca interna and granulosa of the pre-ovulatory follicle.
BUAL induced pathological alterations in lipid and carbohydrate ratios and lipase activity: Special staining of BUAL ovaries for lipid detection revealed lipid accumulation in follicular granulosa, theca cells, oocytes and macrophages.
Immunolocalization of [alpha]-TNF: Considering the importance of the expression of TNF-[alpha] in stimulating, proliferation and steroidogenesis in the ovarian follicle theca cells, this study examined the expression levels of TNF-[alpha], in pre-antral and antral follicles which were observed in the granulosa layer in PCOS ovaries.
In relation, the ES decline in S3 suggested that sub-chronic exposure could disrupt the ES synthesis of theca cells in the ovarian follicles, and the following increase in S4 and S5 confirmed that ES production improved during the recovery period.
Previous studies have reported six morphological characters to use when classifying Siderastrea species: corallite diameter, columella diameter, number of septa, theca thickness, columellar depth, and distance between individual corallites (Laborel, 1970, 1974; Budd and Guzman, 1994; Budd, 1980; Menezes et al.
These were suggestive of theca lutein cysts of pregnancy in both enlarged ovaries in association with the partial hydatidiform mole.
However, the complete development of the oocyte within the follicular structure requires continuous two-way communication between the oocyte and cumulus cells that surround it (cumulus-oocyte complex), as well as other somatic cells included in the follicle, such as theca and the granulosa cells (Eppig et al.
2016); distal portion of the pedicel dilated and cup shaped, hereafter called cupular pedicel; calyx often truncate and entirely surrounding the ovary; corolla slender, tubular, to 10+ cm in length, the tube formed by six free but marginally interlocking petals which are brightly colored (red, orange or yellow); and six epipetalous stamens with dorsifixed anthers that are either tetrasporangiate and longitudinally dehiscent, or each theca secondarily divided by transverse septae and apparently dehiscent through numerous apertures.