Now we will move to the understanding of a normal menstrual cycle.
The ovarian cycle and the uterine cycle
The ovarian cycle and the uterine cycle are two different things happening together and dependent on one another. The ovarian cycle is happening in the ovaries and the uterine cycle in the uterus. The blood flow is due to the effects of the menstrual cycle on the uterine cycle, resulting in a uterine blood flow.
It all begins with the birth of a female child. When a female child is born, she has 100,000 primary oocytes in her ovaries, waiting for puberty when they will become secondary oocytes. After that, with each menstrual cycle they take the form of ova. An ovum is a potential egg that gets fertilizes by a sperm.
100,000 oocytes mean potentially 100,000 menstrual cycles. However, that does not happen. A normal healthful female reproductive life consists of 34-35 years that can be approximately 400 normal menstrual cycles, using only 400 oocytes.
What is menarche?
The beginning of the menstruation with the first menstrual cycle is called menarche. This is the onset of puberty and is marked by the following changes in the female body:
1. Change in body shape
2. Widening of pelvis
3. Typical fat distribution
4. Response of ovaries to the pituitary hormones with secretion of estrogen
5. Growth of the breasts, body hair, and uterus
What is thelarche then?
Thelarche is a term referred to the 2 years preceding menarche. It primarily is characterized by development of the breasts.
Can you tell me about menstruation before we move on the menstrual irregularities?
Estrogen released by the ovary is more specifically released by a mature ovarian follicle. The follicle will cause the release of GnRH from the Hypothalamus in the brain, which will cause the secretion of FSH and LH from the brain’s pituitary gland. These hormones will induce ovulation. Once an ovum is released from a mature follicle in the ovary, it is ready to form a zygote with a sperm. If the sperm can get to the ovum through a normal fallopian tube (one that has either never been ligated or one that has undergone a tubal reversal), there is a chance of fertilization. Fertilization results in a zygote. The follicle left behind will become a Corpus Luteum and begin to secrete progesterone. This is the ovarian part of the cycle.
Now the progesterone will be preparing the uterus to receive a freshly conceived zygote. However, if that does not happen, the follicle finally dies and the uterine tissue starts disintegrating, resulting in blood flow, completing the uterine cycle.
So when do the irregularities occur?
This was a very brief summary of what happens in the cycle. There are a lot of places where things could go wrong, ultimately resulting in menstrual irregularities. We are trying to explain here what happens normally and how many processes need to happen correctly in order to ensure proper menstruation. There may be a hormonal imbalance, a born deformity in the reproductive system, absence of ovulation, or perhaps many other problems that may affect the normal menstrual cycle.
Wait, wait, absence of ovulation? If I am having menses, doesn’t that mean I am ovulating as well?
No, you may or may not be ovulating. Menstrual abnormalities, as noted above, have many causes.
I don’t understand this?
Continue patiently with the rest of the articles in the menstrual irregularities series.