te Velde E R, Scheffer G J, Dorland M, Broekmans F J, Fauser B C
Department of Endocrinology and Fertility, University Hospital Utrecht, Heidelberglaan, The Netherlands.
Mol Cell Endocrinol. 1998 Oct 25;145(1-2):67-73. doi: 10.1016/s0303-7207(98)00171-3.
Supplies of follicles are established during early fetal life and decrease exponentially thereafter by a process called atresia. Subfertility only starts at a mean age of about 30-31 years, when the remaining follicle reserve has become a fraction of its original number. Thereafter, a further decrease in both oocyte quantity and quality dictates the subsequent reproductive events including decrease of fertility, increased abortion rate, the end of fertility, the beginning of cycle irregularity and, when almost no follicles are left, the occurrence of menopause. The same remarkable variation of age at menopause almost certainly is also present for the preceding reproductive events. When quantity and quality of antral follicles drop below a critical threshold, there is a subsequent drop in inhibine B resulting in the selective FSH rise at a mean age of 37-38 years. This FSH rise explains the accelerated follicle depletion, the increased proportion of growing follicles reaching the selectable stage, the shortening of the follicular phase and the increased incidence of dizygotic twinning. The concurring decrease of oocyte quality is in line with the increased incidence of abortions and chromosomal aberrations after age 35.
卵泡储备在胎儿早期就已形成，此后通过一种称为闭锁的过程呈指数级减少。亚生育能力仅在平均年龄约30 - 31岁时开始，此时剩余的卵泡储备已降至原始数量的一小部分。此后，卵母细胞数量和质量的进一步下降决定了随后的生殖事件，包括生育能力下降、流产率增加、生育结束、月经周期开始不规律，以及当几乎没有卵泡剩余时，更年期的出现。对于之前的生殖事件，更年期年龄同样存在显著差异。当窦卵泡的数量和质量降至临界阈值以下时，抑制素B随后下降，导致在平均年龄37 - 38岁时促卵泡生成素选择性升高。这种促卵泡生成素的升高解释了卵泡加速耗竭、达到可选择阶段的生长卵泡比例增加、卵泡期缩短以及双卵双胎发生率增加的现象。卵母细胞质量的同时下降与35岁以后流产和染色体畸变发生率的增加相一致。
