The number of primary eggs are reserved in the outside layer of the ovaries. These primary eggs develop and grow through a nuclear maturation (meiotic divisions) and cytoplasmic process (forming cell organelles) to become matured eggs in different stages of follicles. For a successful pregnancy, nuclear maturation and cytoplasmic process need to take place successfully, which lead to the quality of eggs. The egg quality is directly related to fertilization with sperm, embryo development in oviduct and embryo implantation on uterus. However, the quality of eggs cannot be presented in any shape of a form. Instead, it is indirectly determined by the result of fertilization, embryo development and implantation.
The primary eggs develop and grow in follicles in ovary. The different stages of follicles in ovary provide an important microenvironment for nuclear and cytoplasmic maturation such as nutrient, hormones, growth factors and anti-oxidant enzymes. These factors are considerably related to the quality of eggs. The function of follicles can be improved by various factors such as exercising regularly, consuming proper nutrition and supplements, getting enough rest, and reducing stress. Avoid smoking can also help improve the egg quality by reducing the oxidative stress.
The egg quality and fertility are significantly related to the age of a woman. Under 38 years of age, the quality of eggs are normally high and can result in a successful embryo development, implementation in the uterus and a normal pregnancy. On the other hands, over 38 years of age, the quality of eggs drop down significantly which increases the chance of showing poor embryo development and leads to lower implantation rate and lower chance of getting a normal pregnancy. This is resulting from inadequate microenvironments in follicles, which often cause errors in nuclear maturation and produce genetically abnormal embryos which then can lead to a miscarriage in pregnancy.