tailieunhanh - Polycystic Ovary Syndrome - part 2

Hơn nữa, nang hang vị khoảng 6-8 mm đường kính sản xuất mức độ estradiol và progesterone được tương tự như những người được tìm thấy trong nang preovulatory bình thường,. Cơ chế của phản ứng "quá sớm" để LH vẫn còn được xác định, nó có thể đại diện cho một tác động của tăng insulin | 4 Franks and Hardy ovaries or from polycystic ovaries from ovulatory women only secrete estradiol in response to LH when the follicle has reached 9-10 mm in diameter. By contrast in cells derived from anovulatory women with polycystic ovaries LH stimulated secretion of estradiol and progesterone in granulosa cells from follicles as small as 4 mm 9 . Furthermore antral follicles around 6-8 mm in diameter produced levels of estradiol and progesterone that were similar to those found in the normal preovulatory follicle. The mechanism of this premature response to LH remains to be determined it could represent an effect of endogenous hyperinsulinemia with or without the influence of hyperandrogenism but may also reflect an intrinsic abnormality of the control of follicle development see below . Inappropriate steroidogenesis by prematurely advanced antral follicles may also help explain the slightly but significantly lower levels of serum FSH in anovulatory women with PCOS. Using mathematical modeling it can be predicted that enhanced estradiol production by a proportion of small antral follicles in a cohort would by a negative feedback effect suppress FSH and prevent further development of healthy follicles within that cohort 24 . This would also explain why low-dose FSH presumably by promoting growth of the healthy follicles leads to normal development of a dominant follicle in women with PCOS. 4. EARLY FOLLICULAR DEVELOPMENT IN PCOS The abnormalities of antral follicle number and function are now well documented but the question remains whether there is also an underlying and perhaps more fundamental abnormality of folliculogenesis originating in the preantral and therefore largely endocrine independent stages of development. There is indeed evidence that disordered folliculogenesis also involves the smaller preantral follicles 25 . The observations by Hughesdon made in archived ovarian tissue sections that the numbers of primary and secondary follicles in the .