Theca

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Related to thecal: Thecal cells

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 ?
Contiguous vertebral involvement was commonest MR imaging pattern, followed by disk involvement, paravertebral and epidural abscesses, thecal sac\spinal cord compression and vertebral collapse.
a) Sagittal T2 weighted MR image of the lower spine shows complex presacral mass with a small separate hyperintense cyst communicating with the thecal sac, which could be meningocele (thin arrow).
The thick thecal plates were covered with prominent circular areolae, each with a pore.
apen- Thecal appendage E- Eye Unc- Uncus H- Humeral Vlv- Valva Max.
Eisenackograptus differs from gothograptids in a more complicated proximal end having a thecal ventral list on theca 1 (1), well-developed transverse rods and an ancora sleeve with seams facing out (Bates et al.
Just before ovulation in Graafian follicles, some thecal cells differentiate into hypertrophic cells and the follicular basement membrane fragments.
Magnetic resonance imaging of thoracic and lumbar spine demonstrated an epidural mass extending from T9 through L4, causing spinal cord and thecal sac compression.
Plain MRI cervical spine revealed central disc bulge at C; 2-C3 and C3~C4, right para central bulgheat C5-C6 causing thecal sac compression and central bulge at C6-C7 level.
Magnetic resonance imaging revealed encroachment into the thecal sac and compression of the spinal cord.
Regulation of androgen production in cultured human thecal cells by insulin-like growth factor I and insulin.
A MRI gadolinium-enhanced T1-weighted fat-saturated axial slice at L2/L3 level showed a lobulated avidly enhancing right paraspinal softtissue mass displacing and invading the psoas muscle and erector spinae muscle group and extended to insinuate into the spinal canal, displacing and compressing the thecal sac to the left (Fig.