| 释义 |
Definition of theca in English: thecanounPlural thecae ˈθiːkəˈθikə 1Anatomy
The loose sheath enclosing the spinal cord. 〔剖〕（包裹脊索的）鞘 Example sentencesExamples - The theca contains the cauda equina or nerve roots.
- The vertebral foramen houses the theca and spinal nerves.
- 1.1 The outer layer of cells of a Graafian follicle.
〔剖〕卵泡膜 Example sentencesExamples - The term ‘follicle complex’ has been proposed to include the follicle, basement membrane, and the theca, including its blood vessels.
- The follicle is surrounded by a theca, derived from the stromal compartment of the ovary and is always separated from this compartment, throughout development and final oocyte maturation, by a basement membrane.
2Zoology
A cuplike or tubular structure containing a coral polyp. 〔动〕（珊瑚的）外壁 Example sentencesExamples - Despite its good preservation, this single specimen did not show all aspects of the theca.
- It is notable that both specimens also display asymmetry in the overall structure of their thecae.
- Calices and thecae are commonly intact, but typically lack feeding appendages.
- In the ‘echinoderm’ reconstruction, the theca lies with the convex side upwards and the appendage is interpreted as an anterior feeding arm.
- The theca around the column is smooth, sometimes with weak longitudinal muscles.
3Botany
Either of the lobes of an anther, each containing two pollen sacs. 〔植〕药室，药爿；囊；室；（苔藓植物的）孢蒴 Example sentencesExamples - Each sequence of thecae forms a stipe, or branch, and colonies varied in the numbers of stipes that they possessed.
- The percentage of thecae that dehisced longitudinally varied greatly among rice varieties.
- Stamens are didynamous, but the yellow anthers occur close together, with their divergent thecae spreading to the outside.
- At this stage, at least one theca is already opened, and pollinators are attracted to the flowers.
- As pollinators removed pollen from the thecae, their walls collapsed and the anthers curled down gradually.
Synonyms bag, pouch, bladder, blister
Derivativesadjective The results suggest that intensive regenerative nutrient cycling or external nutrient inputs are a necessary precondition for an efficient trophic transfer of the energy stored in blooms of thecate dinoflagellates. Example sentencesExamples - This is a small thecate dinoflagellate, almost pear-shaped, with a conical anterior end and a round posterior.
- It is a widespread Paleozoic marine taxon that has been interpreted most recently as a tubiculous annelid or other ‘worm’ or as a thecate hydrozoan or scyphozoan cnidarian.
OriginEarly 17th century: via Latin from Greek thēkē 'case'. Rhymesbeaker, Costa Rica, Dominica, eureka, Frederica, Griqua, jobseeker, leaker, loudspeaker, seeker, shrieker, sika, sneaker, speaker, squeaker, streaker, Tanganyika, tikka, Topeka, wreaker Definition of theca in US English: thecanounˈθikəˈTHēkə 1Anatomy
The loose sheath enclosing the spinal cord. 〔剖〕（包裹脊索的）鞘 Example sentencesExamples - The vertebral foramen houses the theca and spinal nerves.
- The theca contains the cauda equina or nerve roots.
- 1.1 The outer layer of cells of a Graafian follicle.
〔剖〕卵泡膜 Example sentencesExamples - The follicle is surrounded by a theca, derived from the stromal compartment of the ovary and is always separated from this compartment, throughout development and final oocyte maturation, by a basement membrane.
- The term ‘follicle complex’ has been proposed to include the follicle, basement membrane, and the theca, including its blood vessels.
2Zoology
A cuplike or tubular structure containing a coral polyp. 〔动〕（珊瑚的）外壁 Example sentencesExamples - In the ‘echinoderm’ reconstruction, the theca lies with the convex side upwards and the appendage is interpreted as an anterior feeding arm.
- Despite its good preservation, this single specimen did not show all aspects of the theca.
- The theca around the column is smooth, sometimes with weak longitudinal muscles.
- Calices and thecae are commonly intact, but typically lack feeding appendages.
- It is notable that both specimens also display asymmetry in the overall structure of their thecae.
3Botany
Either of the lobes of an anther, each containing two pollen sacs. 〔植〕药室，药爿；囊；室；（苔藓植物的）孢蒴 Example sentencesExamples - As pollinators removed pollen from the thecae, their walls collapsed and the anthers curled down gradually.
- Each sequence of thecae forms a stipe, or branch, and colonies varied in the numbers of stipes that they possessed.
- Stamens are didynamous, but the yellow anthers occur close together, with their divergent thecae spreading to the outside.
- The percentage of thecae that dehisced longitudinally varied greatly among rice varieties.
- At this stage, at least one theca is already opened, and pollinators are attracted to the flowers.
Synonyms bag, pouch, bladder, blister
OriginEarly 17th century: via Latin from Greek thēkē ‘case’. |