If we think logically, two things can go wrong at the ovary level. First, the egg is not of good quality and second, the egg is not released (or released infrequently). Let me talk about the first problem in this post.
Poor egg quality is usually age related. The best eggs are recruited and released first and as age advances, the eggs that are released deteriorate in quality. What quality really implies is the competence to form an embryo with potential to implant and lead to a pregnancy.
All our body cells have two copies of each chromosome (that carry the genetic information) and a total of 23 pairs of chromosomes. When an egg and a sperm unite the resulting embryo that will eventually grow into a baby should have a normal number of chromosomes. This can only happen if the egg and the sperms have reduced their chromosomes to one chromosome each of the 23 chromosomes. This is achieved through reduction division also called meiosis. The movement of the chromosomes is achieved with the help of a delicate structure called the meiotic spindle. The spindle is composed of an assembly of elastic threads arranged in an ellipsoid manner (with two poles or ends) and each thread pulls one chromosome towards one pole. The regulatory mechanisms responsible for the assembly of the spindle is altered significantly in older women and this leads to an increasing number of eggs with abnormal number of chromosomes (called aneuploidy), i.e. either one less or one more than the normal figure of 23.
There is very limited that can be done to reverse this decline in egg quality and ovarian reserve. The latest medication which MAY help women with low ovarian reserve is DHEA (dehydroepiandrosterone).
Ovulation disturbances in the next post....