De novo synthesis of all steroid hormones starts with the conversion of cholesterol to pregnenolone by CYP11A (cholesterol side-chain cleavage) .
Prenatally androgenized ewes showed early increase in LH secretion, coupled with progressive loss in reproductive cyclicity and ovulatory failure , increased number of primary follicles , and persistent follicular cysts  along with upregulation of steroidogenic genes such as StAR, CYP11A, and CYP17 in thecal cells of female offspring .
Theca cells derived from PCOS ovaries and propagated in long-term culture demonstrate increased CYP11A expression compared to normal theca cells [54, 55].
, cytochrome P450 11a (cholesterol sidechange cleavage protein); CYP17, cytochrome P450 17 (e.g., 17[alpha]-hydroxylase); E2, 17[beta]-estradiol; EOGRTS, extended one-generation reproductive toxicity study; FSTRA, fish short-term reproductive assay; MEOGRT, Medaka extended one- generation reproductive test; StAR, steroidogenic acute regulatory protein; VO, vaginal opening; VTG, vitellogenin.
(2016) demonstrated that vitrification down-regulated the mRNA levels of ZP3, CYP11A
and anti mullerian hormone (AMH) after short term in vitro culture of isolated follicles derived from cryopreserved human ovarian tissue (30).
The relative mRNA expression levels of StAR, CYP11a, AMH, and Kitlg were calculated by setting the mRNAs levels of [beta]-actin as one.
The mRNA levels of CYP11a gene in groups of B and D were significantly decreased (P < 0.01) compared with the control, while the levels of CYP11a in group C were significantly increased (P < 0.01).
It is well known that CYP11a is the rate-limiting enzyme for testosterone synthesis in Leydig cells .
After granulosa cells of follicle which it will surround become two or more layers, theca differentiation factors (TDFs) released from these cells stimulate mRNA expressions of LH receptors and steroidogenic enzymes (CYP11A
, 3[beta]-HSD CYP17) required for androgen biosynthesis in theca precursor cells.
(1994) Contribution of Ad4BP, a steroidogenic cell-specific transcription factor, to regulation of the human CYP11A
and bovine CYP11B genes through their distal promoters.
The effect on fetal testosterone production has been linked to reduced expression of steriodogenic enzymes (CYP17, CYP11a
, StAR) and insulin-like 3 (INSL3) (Wilson et al.