The menstrual cycle is governed by hormonal changes in the hypothalamus, pituitary gland, and ovaries. It involves the ovarian cycle of follicle development and ovulation, as well as the uterine cycle of proliferation, secretion, and menstruation. The average cycle is 28 days, but can range from 21-45 days. Menarche typically occurs between ages 12-15, while menopause usually occurs between ages 45-55. Fertility is highest around the time of ovulation in the middle of the cycle. The cycle is controlled by hormones like estrogen, progesterone, FSH, and LH to regulate follicle development, ovulation, and preparation of the uterus for potential implantation.

1. Basic Physiology : Menstrual cycle.

2. • The menstrual cycle is the regular natural changes that occurs in the
uterus and ovaries that make pregnancy possible
Cycle is required
for the production of eggs for the preparation of the
uterus for pregnancy
• Common symptoms: acne, tender breasts, bloating , feeling tired ,
irritability and mood changes
• Premenstrual syndrome in 20 to 30 %
3 to 8 % severe premenstrual syndrome

3. The first period menarche
The average age of menarche is 12-15.
They may occasionally start at eight
The typical length of time between 21 to 45
( with average of 28 - bleeding lasts 2 to 7 ).
Factors affect timing are-
genetics
diet
overall health

4. Menopause cessation of menstrual cycles at the end of
a woman’s reproductive period .
Menstruation stops occurring after menopause which usually
occurs between 45 and 55
The average age of menopause 52 years,.
Menopause before age 45 is considered premature in industrial
countries.
The age of menopause is largely a result of cultural and
biological factors

5. The menstrual cycle is gaovern by hormonal
changes.
Menstrual cycle
ovarian cycle uterine cycle
follicular luteal menstruation secretory
phase phase phase
ovulation proliferative
phase

6. Fertility .
Fertile period- ( the time with the highest likelihood of
pregnancy resulting from sexual intercourse ) covers the time
from about 5 days before and until 2 days after ovulation.
In a 28-day cycle with a 14- day of luteal phase corresponds to
the second and the beginning of the third week.
The menstrual cycle can be described by the ovarian or uterine
cycle.
Ovarian cycle describes changes that occur in the follicles of the
ovary
Uterine cycle describes changes in the endometrial lining of the
uterus.

7. Ovarian cycle
Ovarian cycle consists of - follicular phase
- ovulation
- luteal phase
The follicular phase -is the first part of the ovarian cycle. During this
phase the ovarian follicles mature and get ready to release an egg.
This phase overlaps proliferative phase of the uterine cycle.
Process of follicles developing folliculogenesis.
Under the influence of several hormones-one dominant follicle in
the ovary will continue maturity.
The follicle that reaches maturity Graafian follicle
contains the ovum.

9. Ovulation mature egg is released from the ovarian
follicles in the oviduct.
Egg has nearly matured , levels of estradiol reaches a threshold,
above which it is reversed and estrogen stimulated the
production of a large amount of LH. LH surge around
day 12 of the average cycle and may last 48 hours.
Which of the two ovaries -left or right-ovulates appears
essentially random ; no known left and right co-ordinations
exists.
Both ovaries will release an egg, if both eggs are fertilized
fraternal twins.

11. After being released from the ovary, the egg
is swept into the fallopian tube by the
fimbria, which is a fringe of tissue at the
end of each fallopian tube.
An unfertilized egg will disintegrate or
dissolve in the fallopian tube.

12. Fertilization by a spermatozoon - takes place in the
ampulla, the widest section of the fallopian tubes.
A fertilized egg immediately begins the process of
embryogenesis or development.
The development embryo takes about 3 days to reach
the uterus and another 3 days to implant into the
endomterium.
It has usually reached the blastocyst stage at the time
of implantation .

14. Luteal phase
Luteal phase- is the final phase of the ovarian cycle and it
corresponds to the secretory phase of the uterine cycle.
During the luteal phase , the pituitary hormones FSH and LH
cause the remaining parts of the dominant follicle to transform
into the corpus luteum progesterone.
The hormones produced by the corpus luteum also suppress
production of the FSH and LH that the courpus luteum needs
to maintain itself.

16. Consequently , the level of FSH and LH fall quickly over time ,
and the corpus luteum subsequently atrophies.
Falling levels of progesterone trigger menstruation and the
beginning of the next cycle .
From the time of ovulation until progesterone withdrawal has
caused menstruation to begin, the process typically takes about
2 weeks with 14 days considered normal.

17. Uterine Cycle
menstruation proliferative secretory phase
phase
Menstruation (also called menstrual bleeding, menses,
catamenia or a period)- is the first phase of the uterine cycle.
The flow of menses normally serves as a sign that a woman
has not become pregnant.

19. Eumenorrhea denotes normal, regular menstruation that
lasts for a few days.
The average blood loss during menstruation is 35 milliliters
with 10-80 ml considered normal.
Painful ramping in the abdomen , back or upper thighs is
common during the first few days of menstruation.
Dysmenorrhea severe uterine pain during menstruation
is known as and it is most common among adolescents and
younger women .

20. Proliferative phase
The proliferative phase -is the second phase of the uterine
cycle when estrogen causes the lining of the uterus to grow, or
proliferate , during this time .
As they mature , the ovarian follicles secrete increasing amounts
of estradiol and estrogen .
The estorgens initiate the formation of a new layer of
endometrium in the uterus , histologically identified as the
proliferatifve endometrium.
The estrogen also stimulates crypts in the cervix to produce
fertile cervical mucus.

21. Secretory phase
The secretory phase -is the final phase of the uterine
cycle and it corresponds to the luteal phase of the
ovarian cycle.
During the secretory phase , the corpuse luteum
produces progesterone, which plays a vital role in
making the endometrium receptive to implantation of
the blastocyst and supportive of the early pregnancy.

24. Hormonal Control of Ovulation
Menstrual cycle is controlled hypo-thalamo-pituitary
axis.
The pituitary is a small gland the size of a cherry that sits at the
base of the brain, behind the bridge of the nose .
GNRH is secreted from the hypothalamus via venous
channels in a pulsatile manner.
Gonadotrophin Releasing Hormone (GNRH) deca-
peptide (a hormone made up of ten amino acids).
Follicle Stimulating Hormone (FSH) and Luteinising Hormone
(LH) are secreated by the anterior pituitary gland.

25. FSH levels are higher in the early follicular phase
of the menstrual cycle (initiating follicular development-
foliculogenesis ) than in the luteal phase. It has a small peak,
which accompanies the very important Luteinising Hormone
(LH) peak, just prior to ovulation . The anterior pituitary also
secretes LH, which remains at basal levels throughout the cycle
with the exception of the LH peak. The LH peak commences
about 36 h. prior to ovulation, and it last for 24 h. with the peak
occurring 24 h. prior to ovulation.

28. Development of the Graafian Follicle
As the follicles start to develop from Day 1 of the cycle, the
granulosa cells of the follicules start to secrete the hormone oestrogen.
Oestrogen has an effect on many parts of the body and aloes has the
effect of regulating the release of gonadotropins.
As the oestrogen level rises, the FSH secretion is reduced, so
that usually only one follicle matures. This is a negative
feedback.
Various follicles have different sensitivity to FSH, and it is the most
sensitive follicle, which becomes dominant, the one destined to
ovulate.
The other developing follicles undergo atresia. The hormone Inhibin
(type A and B) is also secreted from the ovary and it too has an
inhibitory effect on the pituitary with respect to FSH secretion.

29. The Effect of Oestrogen and Progesterone on the
Endometrium
Circulating oestrogen causes both the glands and the stroma of
the endometrium to proliferate.
Following ovulation progesterone, is released resulting in
secretory changes in the endometrium with tortuous glands
containing lots of glycogen able to provide a welcoming
nutritional environment should an embryo arrive.

30. Ovulation of the Follicle
When the follicle is ready to ovulate, oestrogen primes
the pituitary gland to release LH in a peak.
This is responsible for the release of the ovum from
the follicle about 36h. after the start of the rise and
24h. after the LH peak.
The hormone would more accurately be called
“Ovulatin Hormone “ and that is what Luteinising
Hormone means (as it induces the Corpus Luteum -
yellow body -after ovulation ).

31. When the mature oocyte is released from the ovary, it is about
0. 135 mm in diameter and is surrounded by cells called the
Cumulus Oophorus.
The tissue forming the theca interna and externa ( the human
equivalent to the egg shell) remain as the corpus luteum.
The yellow colour comes from the deposition of carotene in the
cytoplasm of the thecal cells.

32. The Corpus Luteim and Pregnancy
The corpus luteum is respoincible for secretion of hormones
essential for a pregnancy to be established (oestrogen and
progesterone ).
These hormones stimulate the uterine lining (endometrium) to
prepare, in anticipation of an embryo arriving in a few days
time, if a sperm has fertilized the ovum.
It is the combined secretion of oestorgen and progesterone
that induces the secretory changes in the endometrium.
The corpuse luteim has an inherent life span of about 14 days
and as it succumbs in the absence of a pregnancy .

33. Thank you for attention !