Menstrual Cycle Phases Notes

Menstrual Cycle Definition

The cyclic events that take place in a rhythmic fashion during the reproductive period of a woman’s life is called the menstrual cycle. The menstrual cycle starts at the age of 12-15 years, which marks the onset of puberty.

The commencement of the menstrual cycle is called menarche. The menstrual cycle ceases at the age of 45-50 years. The permanent cessation of menstrual cycle in old age is called menopause.

Read And Learn More: Medical Physiology Notes

Duration Of Menstrual Cycle

The duration of a menstrual cycle is usually 28 days. But, under physiological conditions, it may vary between 20 and 40 days.

Changes During Menstrual Cycle

During each menstrual cycle, a series of changes occur in the ovary and accessory sex organs. All these changes are divided into 4 groups for the convenience of description.

1. Ovarian changes
2. Uterine changes
3. Vaginal changes
4. Changes in the cervix.

All these changes take place simultaneously.

Ovarian Changes During Menstrual Cycle

The changes in the ovary during each menstrual cycle occur in two phases.

1. Follicular Phase
2. Luteal Phase.

Follicular Phase

The follicular phase extends from the 5th day of the cycle until the time of ovulation, which takes place on the 14th day. During this phase, there is maturation of the ovum with the development of ovarian follicles through different stages.

Ovarian Follicles

Ovarian follicles are the glandular structures occupying the stroma of the cortex. Each follicle consists of the ovum surrounded by epithelial cells namely granulosa cells.

The follicles gradually grow into matured follicles through various stages:

1. Primordial follicle
2. Primary follicle
3. Vesicular follicle
4. Matured follicle or Graafian follicle.

1. Primordial Follicle

• At the time of puberty, both ovaries contain about 4,00,000 primordial follicles. The diameter of the primordial follicle is about 15-20 p and that of the ovum is about 10 p.
• Each primordial follicle has an ovum which is incompletely surrounded by the granulosa cells. These cells are believed to provide nutrition to the ovum throughout childhood.
• Granulosa cells also secrete the oocyte maturation inhibiting factor which keeps the ovum in the immature stage.
• All the ova present in the ovaries are formed before birth. No new ovum is developed after birth. At the onset of puberty, under the influence of FSH; and LH the primordial follicles start growing through various stages.

2. Primary Follicle

• The primordial follicle becomes the primary follicle when the ovum is completely surrounded by the granulosa cells. During this stage the follicle and the ovum inside
• the follicle increase in size. The diameter of the follicle increases to 30-40 p and that of the ovum increases to about 20 p. The follicle is not covered by a definite connective tissue capsule. The characteristic changes taking place during the development of primary follicles are:

1. The proliferation of granulosa cells and the increase in the size of the follicle
2. Increase in size of ovum
3. The onset of the formation of connective tissue capsule around the follicle.

The primary follicles develop into vesicular follicles.

3. Vesicular Follicle

Under the influence of FSH, about 6-12 primary follicles start growing and develop into vesicular follicles. The changes, which take place during the development of vesicular follicles are:

1. Changes in granulosa cells
2. Changes in ovum
3. Formation of the capsule.

Changes in granulosa cells

1. First, the proliferation of granulosa cells occurs
2. Some irregular spaces appear in between the granulosa cells
3. These spaces fuse to form a cavity called the follicular cavity or antrum
4. An Antrum is filled with a serous fluid called the liquor follicle
5. With the continuous proliferation of granulosa cells, the follicle increases in size
6. Antrum with its fluid also increases in size
7. Ovum is pushed to one side and it is surrounded by granulosa cells which form the germ hill or cumulus oophorus
8. Granulosa cells which line the antrum form membrana granulosa
9. Cells of germ hill become columnar and form corona radiata.

Changes in ovum

1. First, the ovum increases in size and its diameter increases to 100-150 p
2. The nucleus becomes larger and vesicular
3. Cytoplasm becomes granular
4. A thick membrane is formed around the ovum which is called zona pellucida
5. A narrow cleft appears between the ovum and zona pellucida. This cleft is called perivitelline space.

Formation of capsule

The spindle cells from the stroma of the ovarian cortex are modified and form a covering sheath around the follicle. The covering sheath is known as the follicular sheath or theca folliculi.

The theca follicle divides into two layers:

1. Theca Interna
2. Theca externa.

Theca Interna

• It is the inner vascular layer with loose connective tissue. The capillaries develop in this layer and these capillaries come in close contact with membrane granulosa which lines the antrum.
• This layer also contains a special type of epithelial cells with lipid granules and some delicate collagen fibers. The epithelial cells become secretory in nature and start secreting the female sex hormones, especially estrogen. The hormones are released into the fluid of the antrum.

Theca externa

• It is the outer layer of the follicular capsule and consists of thickly packed fibers and spindle-shaped cells.
• After about 7th day of the menstrual cycle, one of the vesicular follicles outgrows the others and becomes the dominant follicle. It develops further to form a Graafian follicle. The other vesicular follicles undergo regression and become atretic by means of apoptosis.

4. Graafian Follicle

A Graafian follicle is a matured ovarian follicle with maturing ovum. It is named after the Dutch physician and anatomist Regnier De Graff. Many changes take place during the development of graafian follicle:

1. The size of the follicle increases to about 1012 mm. It extends through the whole thickness of the ovarian cortex
2. At one point, the follicle encroaches upon tunica albuginea and protrudes upon the surface of the ovary. This protrusion is called a stigma. At the stigma, the tunica albuginea becomes thin
3. The follicular cavity becomes larger and distended with fluid
4. Ovum attains maximum size in the germ hill
5. Zona pellucida becomes thick
6. The corona radiata becomes prominent
7. Small spaces filled with fluid appear between the cells of germ hill outside the corona radiata. These spaces weaken the attachment of the ovum to the follicular wall
8. he ca interna becomes prominent. Its thickness becomes double with the formation of the rich capillary network
9. Some more epithelial cells start secreting the SfTtal more epithelial cells start sex hormones
10. On the 14th Tay of the menstrual cycle, the Graafian follicle is ready for the process of ovulation.

Ovulation

Ovulation is the process in which there is a rupture of the Graafian follicle with the consequent discharge of the ovum into the abdominal cavity. This occurs after the maturity of the follicle. It is influenced by LH. Ovulation occurs usually on the 14th day of the menstrual cycle in a normal cycle of 28 days. The ovum enters the fallopian tube.

Process Of Ovulation

The mechanism of ovulation is not known clearly. The process of ovulation is explained in the next chapter. The process is gradual and occurs in different stages:

1. Rupture of Graafian follicles takes place at the stigma
2. Follicular fluid oozes out
3. Germ hillock is freed from the wall Ovum is expelled out into the abdominal cavity
4. Along with some amount of fluid and granulosa cells
5. From the abdominal cavity, the ovum enters the fallopian tube through the fimbriated end. Other details are given in the next chapter.

The ovum becomes haploid before or during ovulation by the formation of polar bodies. The ovum must be fertilized soon, i.e. within 24-48 hours after ovulation because, only during this time, it is viable for fertilization.

After fertilization, the ovum is called a zygote. From the fallopian tube, the zygote reaches the uterus on 3rd day after ovulation. And, the implantation of the zygote in the uterine wall occurs on 6th or 7th day. If fertilization does not occur, the ovum degenerates. Generally, only one ovum is released from one of the ovaries.

Luteal Phase

This phase extends between the 15th and 28th day of the menstrual cycle. During this phase corpus luteum is developed and hence this phase is called the luteal phase.

Corpus Luteum

The Corpus luteum is a glandular yellow body developed from the ruptured graafian follicle after the release of the ovum. It is also called the yellow body.

Development Of Corpus Luteum

• Soon after the rupture of the Graafian follicle and release of the ovum, the follicle is filled with blood. Now the follicle is called corpus hemorrhagic. The blood clots slowly.
• The corpus hemorrhagic does not degenerate immediately. It is transformed into a corpus luteum.
  The follicular cavity closes gradually by the healing of the wound.
• The blood clot is gradually replaced by a serous fluid containing fibrin. The corpus luteum obtains a diameter of 15 mm and remains in the ovary till the end of the cycle.

Structure Of Corpus Luteum

• In the corpus luteum, the granulosa cells and theca interna cells become larger and are transformed into lutein cells- granulosa lutein cells and theca lutein cells. The process which transforms the granulosa and theca cells into lutein cells is called luteinization.
• Fine lipid granules and yellowish pigment granules are accumulated in the granulosa lutein cells. The yellowish pigment granules give the characteristic yellow color to the corpus luteum. The granulosa lutein cells form the folds in the corpus luteum.
• Theca lutein cells contain only lipid granules and not yellow pigment. The theca lutein cells are placed within the folds formed by granulosa lutein cells.
• Theca externa covers the lutein cells. It sends connective tissue layers, which penetrate between lutein cells. The follicular cavity is greatly reduced with an irregular outline. It is filled with serous fluid and remnants of mood clots.

The function of Corpus Luteum

Secretion Of Hormones

The corpus luteum acts as a temporary endocrine gland. It secretes a large quantity of progesterone and a small amount of estrogen. The granulosa lutein cells secrete progesterone and theca lutein cells secrete estrogen. LH influences the secretion of these two hormones.

Maintenance Of Pregnancy

• If pregnancy occurs, the hormones secreted by the corpus luteum maintain the pregnancy.
• The Corpus luteum is active until the placenta starts secreting estrogen and progesterone. It occurs after about three months of pregnancy. Abortion occurs if the corpus luteum becomes inactive or removed before the third month of pregnancy, i.e. before the placenta starts secreting the hormones.

Fate Of Corpus Luteum

The fate of the corpus luteum depends upon whether the ovum is fertilized or not.

1. If the ovum is not fertilized

• If fertilization does not take place, the corpus luteum reaches the maximum size about one week after ovulation. During this period, it secretes a large quantity of progesterone with a small quantity of estrogen. Then, it degenerates into the corpus luteum menstrual or spurium.
• The cells decrease in size and the corpus luteum becomes smaller and involuted. Afterward, the corpus luteum menstrual is transformed into a whitish scar called corpus albicans. The process by which the corpus luteum undergoes structural and functional regression is called luteolysis.

2. If the ovum is fertilized

• If the ovum is fertilized and pregnancy occurs, the corpus luteum persists and increases in size. It attains a diameter of 20-30 mm and it is transformed into corpus luteum graviditatis (verum) or corpus luteum of pregnancy. It remains in the ovary for 3-4 months.
• During this period, it secretes a large amount of progesterone with a small quantity of estrogen, which are essential for the maintenance of pregnancy. After 3-4 months, the placenta starts secreting these hormones, and corpus lutein degenerates.

Uterine Changes During Menstrual Cycle

During each menstrual cycle, along with ovarian changes, uterine changes also occur simultaneously. The changes in the uterus take place in three phases:

1. Menstrual phase
2. Proliferative phase
3. Secretory phase.

Menstrual Phase

• After ovulation, if fertilization occurs the ovum becomes a zygote and it gets implanted on the uterine wall leading to pregnancy. If pregnancy does not occur, the thickened endometrium is shed or desquamated.
• This desquamated endometrium is expelled out through the vagina along with some blood and tissue fluid. The process of shedding and exiting the uterine lining along with blood and fluid is called menstruation or menstrual bleeding.
• It lasts for about 4-5 days. This period is called menstrual phase or menstrual period. It is also called menses, ammonia, or catamenia.
• The day when bleeding starts is considered the first day of the menstrual cycle.
• Two days before the onset of bleeding, that is on the 26th or 27th day of the previous cycle, there is a sudden reduction in the release of estrogen and progesterone from the ovary. The decreased level of these two hormones is responsible for menstruation.

Changes In Endometrium During Menstrual Phase

1. Lack of estrogen and progesterone causes sudden Evolution of the endometrium of the uterus
2. leading to a reduction in the thickness of the endometrium by up to 65% of the original thickness
3. During the next 24 hours, the tortuous blood vessels in the endometrium undergo severe constriction. Endometrial vasoconstriction is caused of three reasons:
   • The involution of the endometrium
   • The actions of vasoconstrictor substances like prostaglandin released from tissues of involuted endometrium
   • Sudden lack of estrogen and progesterone (which are vasodilators)
4. The vasoconstriction leads to hypoxia which results in necrosis of the endometrium
5. Due to necrosis, the blood vessels of the endometrium start rupturing and blood oozes out
6. The outer layer of the necrotic endometrium is separated and passes out along with blood
7. This process is continued for about 24-36 hours.
8. Within 48 hours after the reduction in the secretion of estrogen and progesterone, the superficial layers of the endometrium are completely desquamated
9. The desquamated tissues and the blood in the endometrial cavity initiate the contraction of the uterus
10. Uterine contractions expel the blood along with desquamated uterine tissues to the exterior through the vagina.

During normal menstruation, about 35 mL of blood along with 35 mL of serous fluid is expelled. The blood clots as soon as it oozes into the uterine cavity. The fibrinolysin causes lysis of clots in the uterine cavity itself so that, the expelled menstrual fluid does not clot.

However, in pathological conditions involving the uterus, the lysis of blood clots does not occur. So the menstrual fluid comes out with a blood clot.

Menstruation stops between the 3rd and 7th day of the menstrual cycle. At the end of the menstrual phase, the thickness of the endometrium is only about 1 mm. This is followed by the proliferative phase.

Proliferative Phase

The proliferative phase extends usually from the 5th to 14th day of menstruation, i.e. between the day when menstruation stops and the day of ovulation. It corresponds to the follicular phase of the ovarian cycle.
At the end of the menstrual phase, only a thin layer (1 mm) of endometrium remains as most of the endometrial stroma is desquamated.

Changes in Endometrium during the Proliferative Phase

1. The endometrial cells proliferate rapidly
2. The epithelium reappears on the surface of the endometrium within the first 4-7 days
3. The uterine glands start developing within the endometrial stroma
4. Blood vessels also appear in the stroma
5. The proliferation of endometrial cells occurs continuously so that the endometrium reaches a thickness of 3-4 mm at the end of the proliferative phase.

All these uterine changes during the proliferative phase occur because of the influence of estrogen released from the ovary. On the 14th day, ovulation occurs under the influence of LH. This is followed by the secretory phase.

Secretory Phase

• The secretory phase extends between the 15th and 28th day of the menstrual cycle, i.e. between the day of ovulation and the day when menstruation of the next cycle commences.
• After ovulation, the corpus luteum is developed in the ovary. It secretes a large quantity of progesterone along with a small amount of estrogen. Estrogen causes further proliferation of cells in the uterus, so that, the endometrium becomes thicker. Progesterone causes further enlargement of endometrial stroma and further growth of glands.
• Under the influence of progesterone, the endometrial glands commence their secretory function. Many changes occur in the endometrium before commencing the secretory function.

Changes In Endometrium During the Secretory Phase

1. The glands of the endometrium become more tortuous the tortuous nature of the glands is because increase in size which exceeds the thickness of the endometrium. So, the glands become tortuous to get accommodated within the endometrium
2. The cytoplasm of stromal cells increases because of the deposition of glycogen and lipids
3. Many new blood vessels appear within the endometrial stroma. The blood vessels also become tortuous
4. Blood supply to the endometrium increases because of the increase in the number and size of blood vessels.
5. Deposition of glycogen increases in the endometrium

• Actually, the secretory phase is the preparatory period during which, the uterus is prepared for implantation of the ovum. At the end of the secretory phase, the thickness of the endometrium is 5-6 mm.
• All these uterine changes during the secretory phase occur due to the influence of estrogen and progesterone.
• Estrogen is responsible for the repair of damaged endometrium and the growth of the glands. Progesterone is responsible for the further growth of these structures and secretory activities in the endometrium.
• If a fertilized ovum is implanted during this phase and, if the implanted ovum starts developing into a fetus, further changes occur in the uterus for the survival of the developing fetus.
• If the implanted ovum is unfertilized or if pregnancy does not occur, menstruation occurs after this phase and a new cycle begins.

Changes In Cervix And Vagina During Menstrual Cycle

Changes In Cervix During Menstrual Cycle

The mucous membrane of the cervix also shows cyclic changes during different phases of the menstrual cycle.

Proliferative Phase

Under the influence of estrogen, during the proliferative phase, the mucous membrane of the cervix becomes thinner and more alkaline. It helps in the survival and motility of spermatozoa.

Secretory Phase

Because of the actions of progesterone during the secretory phase, the mucus membrane of the cervix becomes more thick and adhesive.

Vaginal Changes During Menstrual Cycle

Proliferative Phase

The epithelial cells of the vagina are cornified. Estrogen released from the ovary is responsible for the cornification of vaginal epithelial cells.

Secretory Phase

Vaginal epithelium proliferates due to the actions of progesterone. The vaginal epithelium is infiltrated with leukocytes. These two changes increase the resistance to infection.

Regulation Of the Menstrual Cycle

Regulation of the menstrual cycle is a complex process that is carried out by a well-organized regulatory system. The regulatory system is a highly integrated system that includes the hypothalamus, anterior pituitary, and ovary with its growing follicle. In the whole scenario, the growing follicle has a vital role to play.

Hormones Involved In Regulation

The regulatory system functions through the hormones of the hypothalamic-pituitary-ovarian axis.

Hormones involved in the regulation of the menstrual cycle are:

1. Hypothalamic hormone – GnRH
2. Anterior pituitary hormones – FSH and LH
3. Ovarian hormones – Estrogen and progesterone.

Hypothalamic Hormone

GnRH from the hypothalamus triggers the cyclic changes during the menstrual cycle by stimulating the secretion of FSH and LH from the anterior pituitary.

The secretion of GnRH depends upon two factors:

1. External factors like psychosocial events which act on the hypothalamus via the cortex and many other brain centers
2. Feedback effects of ovarian changes via ovarian hormones.

Anterior Pituitary Hormones

1. FSH and LH secreted from the anterior pituitary modulate the ovarian and uterine changes by acting directly and/ or indirectly via ovarian hormones. FSH stimulates the recruitment and growth of immature ovarian follicles.
2. LH triggers ovulation and sustains the corpus luteum. Secretion of FSH and LH is under the influence of GnRH.

Ovarian Hormones

• Estrogen and progesterone which are secreted by follicles and corpus luteum show many activities during the menstrua; cycle. Ovarian follicle secretes large quantity of n-i uj.;. H and corpus luteum secrete large quantities of progeslerone.
• Estrogen secretion reaches the peak twice in each cycle: once during the follicular phase just before ovulation and another one during the luteal phase. On the other hand, progesterone is virtually absent during follicular phase tile prior to ovulation.
• But it plays a critical role during the luteal phase. Estrogen is responsible for the growth of follicles. Both steroids act together to produce the changes in uterus, cervix, and vagina.
• Both the ovarian hormones are under the influence of GnRH which acts via FSH and LH. In addition, the secretion of GnRH, FSH, and LH is regulated by ovarian hormones.

Regulation Of Ovarian Changes

Follicular Phase

1. The biological clock that is responsible for triggering the cyclic events is the pulsatile secretion of GnRH at about every 2 hours (due to some mechanism that is not understood clearly)
2. The pulses of GnRH release stimulate the secretion of FSH and LH from the anterior pituitary
3. LH induces the synthesis of androgens from theca cells of growing follicle
4. FSH promotes aromatase activity in granulosa cells of the follicle resulting in the conversion of androgens into estrogen. It also promotes follicular development
5. Estrogen is responsible for the development and growth of the Graafian follicle. It also stimulates the secretory activities of theca cells
6. Estrogen also exerts a double feedback control on GnRH
   • Initially, when estrogen secretion is less, it inhibits GnRH secretion leading to a decrease in the secretion of FSH and LH (negative feedback)
   • Later when a large amount of estrogen is secreted by the maturing follicle, it stimulates the secretion of GnRH resulting in the secretion of a large quantity
   • Of FSH and LH (positive feedback). This, in turn, facilitates the growth of Graafian follicles
7. In addition, estrogen shows the following actions:
   • Increases the number of FSH and LH receptors on the granulosa cells of follicles and increases the sensitivity of these cells for FSH and LH
   • Facilitates the faster growth of graafian follicle
8. LH is necessary to provide the final touches for the growth of the Graafian follicle. It stimulates the secretion of estrogen. At the same time, it stimulates the theca cells to secrete progesterone.

Ovulation

LH is important for ovulation. Without LH, ovulation does not occur even with a large quantity of FSH. Prior to ovulation, a large quantity of LH is secreted. The need for excessive secretion of LH for ovulation is known as ovulatory surge for LH or luteal surge.

Luteal Phase

Role of LH

The changes taking place in the ovary after ovulation depend mainly on LH which exerts many actions.

LH:

1. Induces the development of corpus luteum from the follicle (devoid of ovum) by converting the granulosa cells into lutein cells
2. Stimulates corpus luteum to secrete progesterone and estrogen
3. Necessary for the maintenance of the corpus luteum.

Role of FSH

FSH also plays a role during the luteal phase.

FSH:

1. Maintains the secretory activity of corpus luteum
2. Stimulates lutein cells to secrete inhibin which in turn inhibits FSH secretion. If the ovum is not fertilized or if implantation of the ovum does not take place,

The changes in the level of the hormones Produce some effects on the corpus luteum which are:

1. Progesterone and estrogen secreted from the corpus luteum inhibit the secretion of FSH and LH from the anterior pituitary by negative feedback
2. The granulosa lutein cells secrete another hormone called inhibin. Inhibin also inhibits the secretion of FSH and LH by negative feedback
3. In the absence of FSH and LH, the corpus luteum becomes inactive
4. Finally, the corpus luteum regresses by means of luteolysis; so progesterone and estrogen are not available
5. The absence of progesterone and estrogen induces the secretion of GnRH from the hypothalamus
6. GnRH stimulates the secretion of FSH and LH from the anterior pituitary
7. FSH and LH stimulate the new immature follicles resulting in the commencement of the next cycle.

Regulation Of Uterine Changes

The cyclic changes which occur in the uterus during the menstrual cycle are influenced by estrogen and progesterone.

Proliferative Phase

During the proliferative stage, the repair of the damaged endometrium occurs mainly by

the actions of estrogen which cause:

1. The proliferation of cells in endometrial stroma
2. Development of uterine glands and appearance of blood vessels in the endometrial stroma.

Secretory Phase

The secretory phase of uterine changes coincides with the luteal phase of the ovarian cycle. Under the influence of FSH and LH from the anterior pituitary, the corpus luteum secretes a large amount of progesterone and a small amount of estrogen. Progesterone is responsible for endometrial changes along with estrogen during this phase.

Progesterone:

1. Stimulates the growth of endometrial glands and makes them more tortuous
2. Stimulates the growth of blood vessels and makes them also tortuous leading to an increase in blood flow
   to the endometrium
3. Stimulates secretory activities of endometrial glands. Thus, during the secretory phase, the structure, blood flow, and secretory functions of the uterus are influenced by estrogen and progesterone secreted by the corpus luteum.

Menstrua! Phase

If pregnancy does not occur, the menstrual phase occurs:

1. During the last two days of the secretory phase, i.e. two days prior to the onset of menstruation, the secretion of a large quantity of progesterone and estrogen from the corpus luteum inhibits the secretion of FSH and LH from the anterior pituitary by negative feedback
2. In the absence of LH and FSH, the corpus luteum becomes inactive and starts regressing
3. Sudden withdrawal (absence) of the ovarian hormones progesterone and estrogen occurs
4. It leads to menstrual bleeding.

Lack of ovarian hormones causes the release of gonadotropins once again from the anterior pituitary. It results in the onset of the development of new follicles in the ovary and the cycle repeats.

Applied Physiology

Menstrual Symptoms

Menstrual symptoms are unpleasant symptoms with discomfort that appear in many women during menstruation. These symptoms are due to hormonal withdrawal leading to cramps in uterine muscle before or during menstruation.

The common menstrual symptoms are:

1. Abdominal pain
2. Dysmenorrhea (menstrual pain)
3. Headache
4. Occasional nausea and vomiting
5. Irritability
6. Depression
7. Migraine (a neurological disorder characterized by intense headaches causing disability).

Premenstrual Syndrome (PMS)

It is the symptom of stress that appears before the onset of menstruation. It is also called premenstrual stress syndrome, premenstrual stress, or premenstrual tension. It lasts for about 4-5 days prior to menstruation. The symptoms appear due to the salt and water retention caused by estrogen.

Common features are:

1. Mood swinging
2. Anxiety
3. Irritability
4. Emotional instability
5. Headache
6. Depression
7. Constipation
8. Abdominal cramping
9. Bloating (abdominal swelling).

Abnormal Menstruation

1. Amenorrhea – the absence of menstruation during the reproductive period of females
2. Hypomenorrhea – decreased menstrual bleeding
3. Menorrhagia – excess menstrual bleeding
4. Oligomenorrhea – decreased frequency of menstrual bleeding
5. Polymenorrhea – increased frequency of menstruation
6. Dysmenorrhea – menstruation with pain
7. Metrorrhagia – uterine bleeding in between menstruations

Anovulatory Cycle

It is the menstrual cycle in which ovulation does not occur. The menstrual bleeding occurs but the release of ovum does not occur. It is common during puberty and a few years before menopause. When it occurs before menopause it is called perimenopause. If it occurs very often during childbearing years it leads to infertility.

An anovulatory cycle occurs due to a variety of causes and the common causes are:

1. Hormonal imbalance
2. Prolonged strenuous exercise program
3. Sating disorders
4. Hypothalamic dysfunctions
5. Juniors in the pituitary gland, ovary, or adrenal gland
6. Long-term use of drugs like steroidal oral contraceptives.