In the ovarian follicle, LH stimulates theca cells to produce androstenedione. In granulosa cells from small antral follicles, FSH stimulates the synthesis of aromatase (Cyp19) which catalyzes the conversion of theca-derived androstenedione to estradiol.
What stimulates theca?
Theca cells are stimulated by luteinizing hormone (LH), with signaling originating in the hypothalamus of the brain. Gonadotropin releasing hormone (GnRH) is released by projections of the hypothalamus into the anterior pituitary gland.
What hormone do theca cells produce?
Theca cells produce androgens in response to luteinizing hormone (LH). Granulosa cells respond to follicle-stimulating hormone (FSH) mainly by aromatizing androgens to estrogens and to some extent by producing pregnenolone from cholesterol.
Does LH act on theca cells?
LH acts on both granulosa lutein cells and theca lutein cells to increase production of progesterone.
How are theca cells formed?
Theca cells form in the secondary follicles, maintaining follicular structural integrity and secreting steroid hormones. Two main sources of theca cells exist: Wilms tumor 1 positive (Wt1+) cells native to the ovary and Gli1+ mesenchymal cells migrated from the mesonephros.
Do theca cells produce estrogen?
Thecal cells are not capable of producing estrogen but do produce androgens in response to LH, which are then converted into estrogen by follicle stimulating hormone (FSH)-induced aromatase in the neighboring granulosa cells of selected growing follicles.
What happens to theca cells?
During development, the majority of follicles undergo atresia, and the theca cells are often the final follicular cell type to die. For those follicles that do ovulate, the theca cells then undergo hormone-dependent differentiation into luteinized thecal cells of the corpus luteum.
Is theca interna vascular?
Definition of the Ovarian Follicular Theca Layer
The theca interna contains theca endocrine cells; the externa is a fibrous, connective tissue layer derived from fibroblastlike cells. The theca interna/externa also contains vascular tissue, immune cells, and matrix factors (Fig. 1).
What is the function of theca externa cells?
Cells of the theca externa contribute structural support to the growing follicle and maintain cyclic adenosine monophosphate (cAMP)-dependent smooth muscle-like function, which is necessary for successful ovulation of the developed oocyte. Cells of the theca interna are necessary for production of ovarian androgens.
Which hormone is most responsible for triggering ovulation?
Luteinizing hormone (LH), the other reproductive pituitary hormone, aids in egg maturation and provides the hormonal trigger to cause ovulation and the release of eggs from the ovary.
How can I increase my luteinizing hormone?
A B6 supplement, along with B-vitamin rich foods, can also help to increase progesterone. Abnormal levels of FSH or LH can be balanced with daily vitex or white peony supplements, and they work best when prolactin hormone is also elevated.
Which hormone stimulates Oestrogen concentrations to increase?
FSH (follicle stimulating hormone)
Stimulates the ovaries to release oestrogen.
Do granulosa cells respond to LH?
By late in the follicular phase a large number of granulosa cells are present and they are responsive to both LH and FSH. They are now competent to secrete sufficient estradiol to trigger the ovulatory surge of gonadotropins.
Where is theca cells found?
Theca cells are endocrine cells located exclusively in the ovary (Erickson, Magoffin, Dyer, & Hofeditz, 1985). The follicle is the basic functional unit of the ovary, containing a single oocyte and granulosa cells enclosed by a basal lamina.
Can you get pregnant without theca cells?
As described in the classic “two-cells-two-gonadotrophin” theory, LH is needed to provide the granulosa cells with androgen precursors for estradiol biosynthesis. FSH alone can induce follicle growth, but without LH, estradiol levels remain low and pregnancy will not occur.
Do primary follicles have theca cells?
The primary follicle develops into a secondary follicle. … The surrounding theca differentiates into two layers: the Theca interna (rounded cells that secrete androgens and follicular fluid) and a more fibrous Theca externa – spindle shaped cells. The androgens are converted into oestrogen by the granulosa cells.