Ovulation is the process by which a fertilizable egg is expelled from the ovary. This usually occurs in the middle of a menstrual cycle. For an egg to be fertilized, previous ovulation is mandatory.
What is ovulation?
Ovulation is the process by which a fertilizable egg is expelled from the ovary. Ovulation usually occurs once per menstrual cycle. In the course of this cycle, several eggs mature in so-called follicles until they are ready for fertilization. One of these follicles migrates to the ovarian wall and then releases an egg about ten to sixteen days before the next regular menstrual period. This then reaches the fallopian tube where it can be fertilized. This process is hormonally controlled. If more than one ovulation occurs within a cycle, this can lead to multiple pregnancies.
Medical and health roles and functions
Ovulation is a prerequisite for the successful development of pregnancy. Already at birth, between one and two million eggs are laid down in the ovaries of a girl. From the beginning of puberty until the end of menopause, ovulation normally occurs in every monthly cycle. At the beginning of each cycle, the pituitary gland and hypothalamus release hormones that stimulate the maturation of eggs and the formation of follicles. The follicles themselves also begin to produce hormones. In addition to pregnancy-preparing estrogens, this is primarily inhibin, which significantly reduces the ability of the follicles to absorb the appropriate maturation hormones. As a result, the most developed follicle prevents further maturation of the other ten to twenty follicles that developed at the same time. This dominant follicle eventually moves to the surface of the ovary, where the follicle opens outward to release the fertilizable egg. Ovulation is triggered by a sharp increase in hormones produced by the pituitary gland. This occurs in a regular cycle between ten and sixteen days before the next expected menstrual period. Immediately after ovulation, the follicle transforms into the so-called corpus luteum, which produces the hormones of the same name that prepare the uterus for a possible pregnancy. They also cause a slight increase in body temperature, so if a woman takes her temperature regularly, she can determine the time of ovulation relatively accurately.
Diseases, ailments and disorders
Since ovulation is controlled by a complex interaction of a wide variety of organs and hormones, it is easy for disorders to occur that affect a woman’s fertility. For example, diseases of the thyroid gland, liver or kidneys can also affect the female cycle. Malnutrition or excessive exercise can also lead to a lack of ovulation. The same applies to mental illnesses, whereby several factors are often present at the same time. Up to twelve percent of all women of reproductive age suffer from polycystic ovarian syndrome. This is a metabolic disorder caused, among other things, by elevated testosterone levels. It is characterized primarily by the formation of several cysts in the ovaries that can be up to ten millimeters in size. In addition, the cycle is usually very irregular and, in addition to the absence of ovulation, there may also be externally visible symptoms such as acne or excessive hairiness. Women who suffer from obesity are particularly affected by polycystic ovary syndrome. Other risk factors include genetic insulin resistance and type 2 diabetes. The fact that ovulation is hormonally controlled is now also used in contraception. By interfering with a woman’s hormonal balance, it is possible to specifically prevent eggs from maturing to the point where they can be fertilized and ovulation can occur. The use of estrogens and/or progestins counteracts the hormones secreted by the pituitary gland and the hypothalamus, which control the growth of follicles and ovulation in the normal course of a cycle. In addition to the contraceptive pill, contraceptive sticks, the three-month injection, the vaginal ring and contraceptive patches also work according to this principle.Also, the hormonal IUD not only prevents implantation of a fertilized egg in the mucosa, but can partially prevent follicle maturation and ovulation.
