theca noun. ['Ɵi:kǝ] Pl. thecae ['Ɵi:si:]. E17.
[Latin from Greek thēkē case.]
Chiefly Anatomy, Zoology, & Botany.
1. A receptacle, a sheath, a cell; esp. one enclosing some organ, part, or structure, as (a) either of the lobes of an anther, each containing two pollen-sacs; (b) the loose sheath enclosing the spinal cord; (c) a cuplike or tubular structure containing a coral polyp. E17.
2. Anatomy. In full theca folliculi [fǝ'lɪkjʊlʌɪ] [mod. Latin = of the follicle]. An envelope of hormonally active cells enclosing a tertiary (vesicular) or a mature (Graafian) ovarian follicle. M19.

Phrases & comb.:
theca cell tumour Medicine an oestrogen-secreting ovarian tumour, sometimes malignant, consisting of cells like those of the theca folliculi; also called thecoma. theca externa [ɛk'stǝ:nǝ] Anatomy the outer fibrous layer of the theca folliculi. theca folliculi: see sense 2 above. theca interna [ɪn'tǝ:nǝ] Anatomy the inner vascular layer of the theca folliculi.

■ thecal adjective of, pertaining to, or of the nature of a theca M19.

■ thecate adjective having a theca L19.

[TahlilGaran] English Dictionary ▲