The female reproduction system

The female reproduction system is, somewhat simplified, constructed through the interplay of three elements:

  • The hormonal interplay between the pituitary gland in the brain and the ovaries, where the eggs mature and the ovulation takes place.
  • The uterine tubes, where the egg is fertilised and transported to the uterus.
  • The uterus, where the fertilised egg adheres to the endometrium and becomes a pregnancy.

Illustrated is the normal functioning uterus:

Uterus UK

The interplay of the hormones and their influence on the fertility

In the ovaries the egg is matured and fully developed prior to the ovulation. The egg is caught by the uterine tube, which leads the egg to the uterus. If the egg is fertilised, it will adhere to the endometrium in the uterus and further develop. See below:


This process is steered by the hormones. If you know something about the influence of the hormones, it will be easier to understand the examinations and treatments you are going through.

Most of the superior sex hormones are formed in the pituitary gland, which is a gland in the brain. The hormone is transported via the blood to its destination (the organ), where a reaction takes place and a signal is sent back to the pituitary gland. Illustrated below:

Hormones UK

The individual hormones are briefly described:

GnRH-Gonadotropin releasing hormone. GnHR causes release of FSH and LH in the pituitary gland.

FSH (Follicle stimulating hormone) is formed in the pituitary gland and stimulates the growth of the follicles, which mature the eggs.

LH-Luteinizing hormone is formed in the pituitary gland and causes ovulation.

Prolactine is formed in the pituitary gland and is in interplay with the breasts and the ovaries. Prolactine causes growth of the mammary gland during pregnancy and stimulate the milk production after childbirth. A too high level of prolactine can restrain the ovulation.

Estradiol is formed in the ovaries. During a menstrual cycle estradiol causes growth of the en endometrium in uterus. A high level of estradiol in the middle of the cycle results in an increase of LH, which leads to ovulation.

Progesterone. During the menstruationprogesterone together with estradiol prepare the endometrium in uterus to receive the fertilised eggs. During a pregnancy progesterone restrains the contractions of the uterus.

Androgens are formed in the ovaries and stimulate growth of the hair and the sexual instinct. An overproduction of androgens restrains ovulation.

HCG (human chorion gonadotropin) is formed in the placenta and prevents that the follicles are destroyed during pregnancy. We analyse this hormone to find out if you are pregnant.

During the menstruation the ovaries contain several small follicles, each of them containing an egg. The pituitary gland releases the hormone FSH, which leads to development of one single follicle to be approximately 20 mm in size. When the follicle is mature, the ovulating hormone LH is released.

The hormones are interdependent, and for some hormones the rule is that an increase in one hormone results in a decrease in another.

Here you can see how the follicles and the hormones develops throughout a normal menstruation cycle:

Menstruation cycle UK

Here you can read more about:




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