Apoptotic bodies were observed in theca cells
and follicular cells from follicles after ovulation.
Gelatinase activity has been found in the theca cell
of growing follicles and the stroma of ovary (7).
Under control of high pulsatile release of LH, the theca cells
upregulate the expression of steroidogenic acute regulatory protein (StAR), P450 sidechain cleavage (P450scc), 3[beta]-hydroxysteroid dehydrogenase (3[beta]-HSD), and cytochrome P450c17 (CYP17) and increase steroidogenic activity in the theca cells
, thereby producing androstenedione.
Moreover, ovary images in normal animals fully correspond with expected characteristics (e.g., antral cavity, corpus luteum, oocyte, granulosa cells, and internal and external theca cells
) (Figure 3(b)), whereas those from PCOS rats displayed dysfunctional characteristics compatible with a large antral cavity in a cystic follicle and showed decreased granulosa and theca (internal and external) cell layers (Figure 3(b)).
Superoxide dismutase activity has been shown in the granulose and theca cells
of the follicle, where glutathione peroxidase enzyme is localized in follicular fluid (2).
Insulin increases androgen synthesis in ovarian theca cells
with its luteinizing hormone-like action.
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.
Considering that granulose and theca cells
of primary, secondary, and tertiary follicles, as well as the stroma of the rabbit, express thyroid hormone receptors (TRs) and TSH receptors (TSHR) , a direct effect of thyroid hormones and TSH on this tissue could be assumed.
Smooth muscle tumor of the ovary is uncommon, accounting for less than 1% of all ovarian tumors, and it has been proposed to originate from hilar blood vessels, smooth muscle metaplasia of ovarian stromal or theca cells
Preantral follicle has an oocyte, surrounded by multiple layers of granulosa cells which isolate from theca cells
by the basement membrane.
This growth is accompanied by an accumulation of granulosa cell layers surrounding the oocyte, formation of the zona pellucida (ZP), and the differentiation of steroid-secreting theca cells
at the basement membrane [30, 31].