The Menstrual Cycle Phases

Menstrual cycle phases by entiregrade
Menstrual cycle phases by entiregrade

For better understanding, the parts of the menstrual cycle have the following phases:

1. Menstrual phase
2. Proliferative (oestrogenic) phase

3. Ovulatory phase
4. Secretory (Luteal) phase
5. Premenstrual phase

1. Menstrual phase

The first 3 to 5 days of the cycle are characterized by the menstrual flow.

This involves shedding of the mucosal lining of the endometrium and passage of the lining along with the blood and connective tissues.

During this phase, the levels of oestrogen and progesterone are the lowest.

2. Proliferative phase

We also know this phase as the oestrogenic or follicular phase.

The FSH that is secreted from anterior pituitary leads to development of primordial follicle into mature follicles or Graafian follicle.

Graafian follicle secretes oestrogen.

The oestrogen stimulates proliferation of endometrial epithelium (innermost lining of the uterus).

Therefore, this phase is know as proliferative phase.

3. Ovulatory phase

This leads to release of ovum from a Graafian follicle.

4. Secretory phase

We also identify this phase by the name luteal phase.

After ovulation, the corpus luteum starts secreting progesterone.

The progesterone does not proliferate the endometrial lining, rather increases the vascularity.

So the blood vessels in the endometrial lining become enlarged and tortuous.

5. Premenstrual phase

If fertilization does not occur after ovulation, the corpus luteum dies and becomes atretic.

The atretic corpus luteum is naming as corpus albians.

The corpus albians can not secrete progesterone.

So, with the lack of progesterone, the endometrial vessels start degenerating which is followed by shedding of the endometrial epithelium called menstruation.

Note: If fertilization occurs, the corpus luteum does not die.

But it keeps on producing progesterone.

The endometrial lining does not shed.
So there is a cessation of menstruation during pregnancy.

Safe period (1-10 days after menstruation)

This is the supplementary topic to let you know about natural contraceptive.

This is the period during which sexual act can be done without the use of other contraceptive measures with no or minimal risk of pregnancy.

If a woman has a regular pregnancy of 28 days, then the unsafe period is from 10th to 18th day of the cycle.

Rest of the period is safe.

However, this varies if the menstrual period is irregular.

With the irregularities in the cycle, the unsafe period increases.

In this case, we can calculate the beginning of the unsafe period by subtracting 18 from the shortest cycle,

And ending of the unsafe period by subtracting 10 from the longest cycle.

In this way, we can find out the safe period.

Suppose a woman has an irregular menstrual cycle that varies from 25 to 40 days.

So 25 is the duration of the shortest cycle and 40 is the duration of the longest cycle.

Her unsafe period is thus from the 7th (25-18) day to 30th (40-10) day of the cycle.

Rest of the period is safe. But mind it, sex with unprotection is always dangerous.

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