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and Consultant Of Ob & Gyn.

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1 and Consultant Of Ob & Gyn.
THE MENSTRUAL CYCLE By BY: DR. MALAK AL-HAKEEM Assistant Professor and Consultant Of Ob & Gyn.

2 Each cycle represents a complex interaction between the hypothalamus, pituitary gland, ovaries and endometrium.

3 Cyclic changes of gonadotrophins Induce functional and morphologic changes in the ovary, resulting in follicular maturation, ovulation and corpus luteum formation with production of steroid hormones.

4 Similar changes at the level of endometrium allow for successful implantation of the embryo.

5 PITUITARY GLAND Consists of two main parts
adenohypophysis (anterior lobe) and neurohypophysis (post. lobe) The posterior lobe transport oxytocin and vasopressin (antidiuretic hormone) from the hypothalamus to their release into the circulation.

6 The blood supply to the pituitary stalk known as the hypophyseal - pituitary portal system represents a major way of transport for hypothalamic secretions to the pituitary.

7 The anterior pituitary produces six protein hormones, F. S. H, L. H, T
The anterior pituitary produces six protein hormones, F.S.H, L.H, T.S.H., G.H, A.C.T.H and Prolactin. FSH, LH and TSH are glyco-proteins each consists of α and ß chain. The α chain is identical in all while the ß chain is specific for each one.

8 All hormones produced by the anterior pituitary are under stimulatory effect by the hypothalamus except prolactin which is under chronic inhibition by hypothalamic Prolactin inhibitory factor (dopamin).

9 HYPOTHALAMUS Produces five hormones or factors, GnRH and PIF have direct effect on menstrual cycle. GnRH stimulates synthesis and release of FSH and LH by the gonadotrophs cells of the pituitary gland.

10 GnRH is a decapitate secreted by the hypothalamus in a pulsatile fashion every 90 minutes.
Continuous infusion of GnRH results in reversible inhibition of gonadotrophins secretion (down regulation or desensitization of pituitary gonadotrophs).

11 Estradiol enhances hypothalamic release of GnRH
while gonadotrophins have an inhibitory effect on GnRH release.

12 The hypothalamus also produces PIF which exerts chronic inhibition of prolactin release from lactotrophs. TRH stimulates prolactin release, this explains the association between primary hypothyroidism and hyper-prolactinaemia.


14 OVARIAN CYCLE In the first half of the menstrual cycle, the anterior pituitary secrets FSH and LH FSH stimulates the growth of several primary follicles in both ovaries.

15 Only one follicle reaches maturation to form the graffian follicle which secrets increasing amount of estrogens mainly estradiol.


17 The increasing level of oestrogen first inhibits FSH production (negative feed back) then stimulates the production of LH surge (positive feed back) which reaches a peak about 48 hours before ovulation.

18 LH surge leads to ovulation and formation of corpus luteum.
LH maintains the growth of corpus luteum and stimulates it to secret oestrogen and progesterone.

19 The corpus luteum has a limited life span (in the absence of pregnancy) after which it degenerates.
Degeneration of corpus luteum and drop in the level of oestrogen and progesterone cause separation of endometrium and menstruation.

20 The drop in the level of these hormones stimulates
the hypothalamus and pituitary to secret GnRH and gonadotrophins to start a new cycle.

21 Follicular Development
FSH receptors are present on the granulose cells. FSH stimulates the growth and maturation of the follicles , it also stimulates the production of aromataze enzymes.

22 LH receptors are present initially on theca cells
LH receptors are present initially on theca cells. LH stimulates it to produce androgens which diffuse into granulose cells to be converted into estrogen by aromataze enzymes.

23 Estrogens (mainly estradiol) increase the no
Estrogens (mainly estradiol) increase the no. of FSH receptors on granulosa cells and increase its sensitivity. Eestrogen and FSH stimulate granulosa cells to form LH receptors.

24 The follicle which is chosen to mature and ovulate has rich estrogen milieu and high FSH content in it’s follicular fluid. The follicle which undergoes atresia are androgen predominant and have low FSH content in it’s follicular fluid.

25 Ovulation As a result of LH surge and h later ovulation takes places and the mature ovum surrounded by corona radiate expels from the ovary.

26 Corpus Luteum Formation
After ovulation and under the effect of LH both granulose cells of the collapsed ruptured follicle and the theca cells undergoes lutinization to form corpus luteum.

27 The corpus luteum secrets large amount of progesterone and oestrogen hormones.
The normal life span of c. luteum is 14 days. After this time it regresses (unless pregnancy occurs), menstruation ensues and the corpus luteum becomes the corpus albicans.

28 The Endometrium Cycle Functionally the endometrium is divided into two zones: Function outer zone that undergoes cyclic changes during menstrual cycle and is sloughed off during menstruation. It is supplied by spiral arteries which are branches from basal arteries.

29 Basal inner zone which remains unchanged during menstrual cycle, after menstruation it provides stem cells for the renewed of the functioning zone.

30 A. MENSTRUAL PHASE Two to seven days during which the superficial layer separate leaving the basal layer from which the endometrium regenerates again.

31 B. Proliferative or oestrogenic phase.
Starts after the end of menstruation and ends at ovulation and is characterized by: Thickness of endometrium 3-4 mm Glands increase in number and length, but remain tubular.

32 The stroma cells proliferate and show mitosis.
Vascularity increase, the spiral arteries increase in length and traverse the whole endometrium.

33 C. Secretary or Progestogenic Phase
Fixed duration irrespective of the length of the cycle (14-12) Begins at ovulation and ends by onset of Menstruation. It is characterized by: Thickness of endometrium 6-8 mm.

34 Glands continue to grow and become tortuous, so it appear like corkscrew or saw-tooth appearance in longitudinal section. The lumen is distended with secretion (glycogen and mucin)

35 The epithelium cells become high colummnar
The epithelium cells become high colummnar. Secretory granules appear first as sub nuclear vacuoles and later as supranuclear vacuoles.

36 Stroma cells increase in size become closely packed together and polygonal. The stroma becomes differentiated into three layers. 1-Superficial compact layer around the neck of glands.

37 Middle spongy layer around the distended lumen of the glands.
Deep compact layers around the basal part of the glands. Marked increase in vascularity with marked elongation of the spinal arteries.

38 Mechanism of Menstruation
Degeneration of C. luteum leads to drop in the level of oestrogen and progesterone. These lead to shrinkage of the endometrium causing increase coiling of the spiral arteries (end arteries) with stasis and ischemia causing necrosis of the superficial and middle layers of endometrium which separate leading to bleeding.

39 The basal layers does no separate as it is supplied by basal arteries which anastemose freely.
Normally the endometrium contains prostaglandins which show marked increase immediately before and during menstruation.

40 There are four prostaglandins present in the endometrium.
PG F2 and thromboxan both are vasoconstrictors and reduce menstrual loss. PGE2 and prostacyclin both are vasodilator and cause heavy menstrual loss.

41 Cyclic changes in cervical mucus
A. In the follicular phase under oestrogen effect the cervical mucus become excessive, watery, less viscid, clear and a cellular. It is stretchable and can reach a length of 10-15cm. just before ovulation (spinbarkite test) It gives positive fern test when dried on a slide.

42 B. In the luteal phase, progesterone makes cervical mucus scanty, viscid, cellular, non stretchable and gives a negative fern test.


44 Cyclic Changes in the vagina
Vaginal smear taken from lateral vaginal fornix shows different pictures according to the phase of the cycle. In the follicular phase the smear consists of many superficial cells with acidophilic cytoplasm and pyknotic nucleus. The back ground is clear with few leucocytes .

45 In the luteal phase the smear consists mainly of intermediate cells with folded edges (navicular cells). These cells have basophilic cytoplasm and vesicular nucleus. The back ground is unclear with many leucocytes.


47 Normal Menstruation Duration: 2-7 days
Length of cycle: 3-5 weeks with weeks as an average. Amount: mls. loss more than 80 mls is abnormal.

48 Consistency Consists of blood rich in leucocytes, endometrial fragments, cervical mucus, desquamated vaginal epithelium cells, bacteria and enzyme. Normally the menstrual blood does not coagulate due to the presence of enzyme produced by endometrium which digest fibrin.

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