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yOur Reproductive Cycle:  • Menstrual Cycle  • Hormonal Cycle  • Ovarian Cycle  

During the reproductive cycle, your body releases an egg, prepares itself for fertilization of the egg by sperm and creates an environment in the uterus in which the fertilized egg could implant and form a developing embryo (ultimately, a baby). If the egg is not fertilized, the lining of the womb is discharged from the body - that's your period. It's a pretty amazing thing going on inside us women. Let's see how it works.

Girls start to have their periods (to menstruate) around the age of 13, usually about 2 years after breasts first start to develop, and continue having periods until menopause, which occurs, on average, at about the age of 51.

The length of the reproductive cycle can vary from a short cycle of only 21 days to a long cycle of 40 days. The length of the cycle is calculated by counting the first day of bleeding as day 1 and then counting until the very last day before the next bleed (period). Even though, the length of the reproductive cycle varies among women, it is commonly described as 28 days.

There are three parts to the reproductive cycle: the menstrual cycle, the hormonal cycle and the ovarian cycle. In the diagram below, you can see the changes taking places during each cycle. (skip down to diagram)

Menstruation takes place during the first 5 days of the cycle – that's when blood, mucus, and tissues are discharged from the uterus; this commonly lasts from day 1 to day 5. During this phase, if fertilization of the egg hasn’t happened, the lining of the uterus, which is called the endometrium, comes away from the uterus wall and the blood and tissues pass out through the vagina. Most women bleed for between 3 and 5 days. The lining of the endometrium will end up about 1 mm thick at the end of the period. As well as the loss of the endometrial tissue, about 35 to 50 ml of blood is lost from the broken endometrial blood vessels in a typical period. This blood does not usually clot unless bleeding is very heavy.

On the 5th day, the endometrium starts regrowing. About 3 to 30 follicles grow between days 8 and 10. Each follicle contains an egg, but by days 10 to 14 one follicle has overtaken the rest and has reached the correct stage of maturity.

During days 6 to 14, the lining of the uterus is repaired and, as can be seen on the diagram, builds up to be thicker. This phase is called the proliferative phase. As the selected follicle develops, it begins to produce estrogen on about the 7th day. Estrogen enters the circulation and influences the growth of the endometrium. The lining of the uterus will now be about 3 mm thick and is also more velvety again.

On about the 14th day of the menstrual cycle, the combined increases in concentration of FSH and LH and estrogen induce ovulation – the bursting of the mature follicle and the release of the immature ovum into the uterine tube (also called fallopian tube). The other follicles over-ripen and break down.

Some women can feel a pain on one side of the abdomen around the time the egg is released. This is known as ‘mittelschmerz’ – a German word translating as ‘middle pain’. An egg is released from the right or left ovary at random and takes about 5 days to travel down the fallopian tube to the uterus.

After the follicle ruptures as it releases its egg, it closes and forms a corpus luteum. The corpus luteum secretes more and more progesterone, which acts on glands in the endometrium and causes them to secrete. The purpose of this secretion is to feed the developing egg until a placenta has formed. Even if the egg is not fertilized and pregnancy has not happened, the secretion is still produced. The progesterone secreted by the corpus luteum causes the temperature of the body to rise slightly until the start of the next period.

If there is no fertilization, the corpus luteum lasts about 14 days and then starts to break down, begins to curl in on itself, forming the corpus albicans. This is when progesterone production rapidly drops and the estrogen level decreases. This lack of hormones causes blood vessels in the endometrium to go into spasm and they cut off the blood supply to the top layers of the endometrium. Without oxygen and nutrients from the blood, the endometrial cells begin to die, tissue breaks down and there is bleeding from the damaged blood vessels. The broken tissue (or menstruum), secretions, blood and one or more unfertilized eggs make their way toward the vagina.

And, the cycle starts again.

diagram of yOur reproductive cycle: ovarian cycle, hormonal cycle, menstrual cycle
source: the image above was reproduced and modified from: The Anatomy Coloring Book, Wynn Kapit and Lawrence M. Elson
 
 
Overview of yOur Cycles:

Ovarian Cycle

Hormonal Cycle

Menstrual Cycle
Primordial Follicle: the primary form of egg with one layer of cells surrounding it

Primary Follicle: during this stage, the primary egg completes its growth

Secondary Follicle: full-size follicle with more cell layers surrounding it

Mature Follicle: final stage of differentiation of the egg

Ovulation (Ovum): mature follicle bursts and releases egg (ovum)

Corpus Luteum: the yellow glandular mass that is formed by the mature follicle once it has discharged its ovum. The corpus luteum secretes progesterone.

Corpus Albicans: an unfertilized corpus luteum that has curled inward on itself

FSH: follicle-stimulating hormone – stimulates the development of ovarian follicles (developing eggs in their sacs) and stimulates the release of estrogen

LH: luteinizing hormone – acts with follicle-stimulating hormone to stimulate sex hormone release.

Estrogen – helps to produce an environment suitable for the fertilization, implantation and nutrition of the early embryo, and is responsible for the development of the female secondary sex characteristics.

Progesterone – is produced in the corpus luteum to counteract estrogen. Promotes the development of new parts of the uterine lining and the implantation of the early. It also prevents further follicular development (no more eggs developing at this time).

Phases
Menstruation: The cyclic discharge through the vagina of blood and tissues from the nonpregnant uterus.

Proliferative: The phase of the menstrual cycle when the follicles in the ovary grow and form an egg; the lining of the uterus is repaired and thickens; there is a surge of hormones, and ovulation occurs.

Secretory: In this phase hormone secretions prepare to feed the developing embryo until a placenta has formed.

If fertilization has not occured, the corpus luteum starts to break down; progesterone and estrogen levels decreases, and blood and tissue are discharged in menstruation.

 
sources: the information on this page was compiled and paraphrased from: myDr (for a Healthy Australia); The Anatomy Coloring Book, Wynn Kapit and Lawrence M. Elson. 

Please note: vaginaverite.com is not moderated by any health or medical experts. for medical questions, please see your doctor. Each of us is unique in our bodies and our experiences, so only an examination by a doctor will give you the specific answers you need.

That said, there's lots to talk about and much to learn about our bodies. The intention of this section is to provide a forum for conversation about our personal experiences, as well as a gateway to information and services available – and to highlight areas of health concern particular to women that need more attention from the medical and research communities.  Feel free to send in suggestions or questions you'd like to see discussed.

 
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