The document discusses the hormonal regulation of ovulation, pregnancy, and parturition. It describes the key hormones involved in each process, including estrogen, progesterone, LH, FSH, hCG, relaxin, corticotropin, and oxytocin. Ovulation is regulated by the hypothalamus and pituitary gland releasing hormones like LH and FSH. Pregnancy involves changes in the maternal body and is maintained by hormones like estrogen, progesterone, hCG, and corticotropin. Parturition is triggered by a drop in progesterone and rise in oxytocin, relaxing ligaments and stimulating uterine contractions.

1. Session: 2015
C.C.E-1st
Paper: Second
Gamete Biology, Development and Differentiation
Topic : HORMONAL REGULATION OF OVULATION,
PREGNANCY, PARTURITION.
Submitted To: Submitted By:
Sudarshan Gokhale
M.Sc Zoology IV Sem

2. SYNOPSIS
 INTRODUCTION.
 WHAT ARE THE PHASES OF OVULATION?
 WHEN DOES OVULATION OCCUR?
 HORMONES REGULATION OF OVULATION.
 Oestrogens Hormone
 Progesterone Hormone.
 Relaxin Hormone.
 PREGNANCY.
 MATERNAL CHANGES DURING PREGNANCY.
 HORMONAL REGULATION OF PREGNANCY.
 Role of Oestrogens, progesterone in Pregnancy.
 Human Chorionic Gonadotropin Hormone(hCG)
 Corticotropin Hormone.
 Oxytocin Hormone.
 PARTURITION.
 Role of Hormone in Parturition.
 Conclusion.
 Reference.

3. OVULATION
 Ovulation is one part of the female menstrual cycle whereby a
mature ovarian follicle (part of the ovary) discharges an egg
(also known as an ovum, oocyte, or female gamete). It is
during this process that the egg travels down the fallopian tube
where it may be met by a sperm and become fertilized.
Ovulation is controlled by part of the brain
called the hypothalamus, which sends signals
that instruct the anterior lobe and pituitary gland
to secrete luteinizing hormone (LH) and follicle-
stimulating hormone (FSH).

5. WHAT ARE THE PHASES OF OVULATION.
The entire ovulation phase is actually defined by a period of elevated
hormones during the menstrual cycle. The process itself can be informally
divided into three phases:
1 • Pre-ovulatory (follicular phase)
2
• Ovulatory (ovulation phase)
3
• Postovulatory (luteal phase)

6. 1. Pre-ovulatory (follicular phase): A layer of cells around
the ovum begins to mucify (become more mucous-like)
and expand, and the uterus lining begins to thicken.
2. Ovulatory (ovulation phase): Enzymes are secreted
and form a hole (or stigma) that the ovum and its network
of cells use to exit the follicle and eventually enter the
fallopian tube. This is the period of fertility and usually
lasts from 24 to 48 hours.
3. Postovulatory (luteal phase): A hormone called LH or
luteinizing hormone is secreted. A fertilized egg will be
implanted into the womb, while an unfertilized egg slowly
stops producing hormones. In addition, the lining of the
uterus begins to break down and prepares to exit the body
during menses

7. WHEN DOES OVULATION OCCUR?
 A woman's menstrual cycle lasts between 28 and
32 days on average.
 The beginning of each cycle is considered to be
the first day of her menstrual period (menses).
Ovulation itself generally occurs between day 10
and day 19 of the menstrual cycle, or 12 to 16 days
before the next period is due.

9. HORMONES REGULATION OF
OVULATION
 Certain species have one or two Oestrous Cycle per year.
 Only Primates possess Menstrual periods, others have
Oestrous cycle.
 Corpus Luteum secrets Oestrogen and Progesterone
 There are following Hormones which are Regulated in the
Ovulation:

10. OESTROGEN
 Oestrogen is a hormone present throughout the cycle in
varying levels.
 The maturing follicle produces estrogen.
 This causes the hypothalamus to send signals to the
pituitary gland to increase production of(LH) Lutenizing
hormone.
 Oestrogen also stimulates the female reproductive
organs to prepare for possible fertilization.
 This produces observable characteristics which can be
monitored to determine fertility.

11. FUNCTIONS OF OESTROGEN
 Responsible for all the Puberty changes such as Growth of Uterus,
Startification of vaginal epithelium, secretion and ciliary movement of
Fallopian tube etc.
 Responsible for the Proliferative stage of menstruation.
 Growth of Uterus during Pregnancy.
 Exerts synergistic action with Oxytocin.
 Oestrogens are responsible for the development of the female
secondary sexual characteristics that distinguish the Female from the
Male.
 Effect on Bone growth.
 Breast development.
 External genitalia growth
 Fat deposition.
 Increase protein anabolism.
 Decrease blood cholesterol.
 Feminizes brain.

12. PROGESTERONE HORMONE
Progesterone is a steroid hormone released by the corpus
luteum that stimulates the uterus to prepare for pregnancy.
Progesterone is the Active Principle of Corpus Luteum.
Sources: Corpus Luteum, Placenta, Adrenal Cortex.
The synthesis of Progesterone from Cholesterol by the
placenta is important to the maintenance of Human
pregnancy after first trimester when ovarian functions
decline.

13. SYNTHESIS OF PROGESTERONE.
 Progesterone is Secreted by the Corpus Luteum
and the Placenta.
 Secreted Progesterone is possibly bound to
Protein.
 The synthesis of Progesterone from Cholesterol by
the placenta is important to the maintenance of
Human pregnancy after first trimester when ovarian
functions decline.

14. FUNCTIONS OF PROGESTERONE
 Progesterone is essential for the maintenance of
pregnancy and other changes associated with it.
 It also take part in Menstruation.
 Responsible for Premenstrual changes of Uterine
Mucosa.
 Take an essential part in Pregnancy
 a. Embedding of Ovum: Progesterone secreted by the
Corpus Luteum is responsible for the premenstrual
Hypertrophy of the Endometrium which is essential for
the reception and embedding of the fertilized ovum.

15. RELAXIN HORMONE
 Relaxin: A hormone that is produced
during pregnancy that facilitates the birth process.
 Relaxin also inhibits contractions of the uterus and
may play a role in determining the timing of
delivery.
 Relaxin is a water-soluble polypeptide hormone
present in pregnant Mammalian ovary, placenta
and uterus.
 Relaxin level of blood reaches maximum at the
terminal stage of Pregnancy.

17. SYNTHESIS
 In the female, it is produced by the corpus luteum of
the ovary, the breast and, during pregnancy, also by
the placenta, chorion, and decidua.
 In the male, it is produced in the prostate and is
present in human semen.

18. FUNCTIONS OF RELAXIN
 In females relaxin is produced mainly by the corpus
luteum, in both pregnant and nonpregnant females; it
rises to a peak within approximately 14 days
of ovulation, and then declines in the absence of
pregnancy, resulting in menstruation.
 During the first trimester of pregnancy, levels rise and
additional relaxin is produced by the decidua.
 Relaxin's peak is reached during the 14 weeks of the
first trimester and at delivery.
 It is known to mediate the hemodynamic changes that
occur during pregnancy, such as increased cardiac
output, increased renal blood flow, and increased
arterial compliance.
 It also relaxes other pelvic ligaments.
 It is believed to soften the pubic symphysis.

19. PREGNANCY
 Pregnancy, also known as gravidity or gestation,
is the time during which one or
more offspring develops inside a woman.
 A multiple pregnancy involves more than one
Pregnancy can occur by sexual
intercourse or assisted reproductive technology.
 The Youngest Age at which child birth has been
reliabily reported is 4 years 8 months.
 This is the case of a girl name LINA MEDINA(1939)
of Peru.

20. MATERNAL BODY CHANGES DURING
PREGNANCY.
 During pregnancy the Uterus enlarge considerably.
It increases to about 1kg at full term.
 The Maternal blood volume increases to 30%
during pregnancy.
 The Heart appears to enlarge during pregnancy.
 The Cardiac output also increases.
 The Breast is to estimulate to secrete milk.This is
done by a hormone Prolactine.
 Oxygen consumption is increases during pregnancy
to satisfy the needs of the Fetus.

21. DURATION OF PREGNANCY.
 The Average duration of Human pregnancy is about
280 days(10Menstrual cycle).
 When calculated from the 1day of the last
menstrual cycle.
 266-270 when calculated from the time of
Ovulation.

22. DURATION OF GESTATION ARE SHOWN IN THE
FOLLOWING TABLE:

23. HORMONAL REGULATION OF
PREGNANCY
 During Pregnancy hormones play a significant role in
triggering changes in the Mother and Fetus.
 Hormones maintain the linning of the Uterus and
prevent Menstruation.
 Hormone increases Flexibility of the Pubic Symphysis.
 Hormone determine the timing of Birth.
 These are following Hormones which are regulate in
pregnancy:
 1.Oestrogen Hormone.
 2.Progesterone Hormone.
 3.Relaxin Hormone.
 4.Human Chorionicgonadotropin Hormone.
 5.Corticotropin Hormone.

24. ROLE OF OESTROGEN HORMONE IN
PREGNANCY
 Oestrogens, Progesterone, Relaxin Hormones play
a vital role in Pregnancy.
 1.The oestrogenic group of hormones comprises
three hormones
 (a) Estradiol: It is the most active hormone present
in almost all Vertebrates.
 (b) Estrone: It is a circulating hormone.
 (c) Estriol: It is found in the Urine of Pregnant
women and in the Placenta.

26.  2.Progesterone is a luteal hormone which is synthesized
by Corpus luteum, adrenal cortex, placenta.
 Progesterone is a pregnancy hormone which acts on
genital tissue and induces proper functioning of Breast.
 3.Relaxin is also produced by the corpus luteum which is
causes softening of Epiphysis and facilitates delivery.
 Small quantity of relaxin also occur in the placenta.
ROLE OF PROGESTERONE
AND RELAXIN HORMONE IN
PREGNANCY

27. HUMAN CHORIONIC GONADOTROPIN
HORMONE
 The hormone human chorionic gonadotropin (better
known as HCG) is produced during pregnancy.
 It is made by cells that form the placenta, which
nourishes the egg after it has been fertilized and
becomes attached to the uterine wall.
 Levels can first be detected by a blood test about 11
days after conception and about 12 – 14 days after
conception by a urine test.
 In general the hCG levels will double every 72 hours.
 The level will reach its peak in the first 8 – 11 weeks of
pregnancy and then will decline and level off for the
remainder of the pregnancy.

28. FUNCTIONS OF HCG HORMONE
 Human chorionic gonadotropin hormone(hCG) enhances
maternal breast growth by increasing protein synthesis.
 Hcg increases maternal fatty acid for ATP production, leaving
more glucose available for Fetus.
 HCG helps to maintain pregnancy and affects the
development of baby (fetus).
 The amount that hCG increases early in pregnancy can give
information about your pregnancy and the health of your baby.
Soon after delivery, hCG can no longer be found in your blood.


30. CORTICOTROPIN HORMONE-RELEASING
HORMONE
 Corticotropin-releasing hormone (CRH) also
known as corticotropin-releasing factor (CRF)
or corticoliberin is a peptide hormone and neuro
transmitter involved in the stress response. It
belongs to corticotropin- releasing factor family.
 In humans, it is encoded by the CRH gene.
 CRH is secreted by the para ventricular
nucleus (PVN) of the hypothalamus in response to
stress.

31. FUNCTION OF CORTICOTROPIN
HORMONE-RELEASING HORMONE
 CRH is also synthesized by the placenta and
seems to determine the duration of pregnancy.
 In the placenta, CRH is a marker that determines
the length of gestation and the timing of
parturition and delivery.
 CRH may act as a trigger for parturition

32. OXYTOCIN HORMONE
 The hormone oxytocin plays a key role in labour.
 Often called the ‘love hormone’, oxytocin is associated with feelings
of bonding and motherhood.
 This is also true of another hormone released during labour
called prolactin.
 If labour needs to be induced (brought on artificially), oxytocin or a
synthetic oxytocin equivalent is often administered to ‘kick-start’ the
process.
 Oxytocin levels rise at the onset of labour, causing regular
contractions of the womb and abdominal muscles.
 Oxytocin induced contractions become stronger and more frequent
without the influence of progesterone and oestrogen, which at high
levels prevent labour.

33. PARTURITION
 The Process by which the(Fetus) Baby is Expelled
from the body of the Mother is called Birth or
Parturition.
 It is also called as Labour or Delievery.
 These are following Hormone which are regulate in
Parturition:
 (a) Oestrogen Hormone.
 (b) Progesterone Hormone.
 (c) Oxytocin Hormone.
 (d) Relaxin Hormone.
 (e) Prolactin Hormone.

35. ROLE OF HORMONES IN PARTURITION
 Oestrogens stimulate the contration of the Uterine
Muscles.
 Oxytocin secreted by the Pituitary gland
accelerates the contraction of Uterine muscles.
 It is released in large amounts after distension of
the cervix and uterus during labor,
facilitating birth, maternal bonding, and, after
stimulation of the nipples.
 Oxytocin is also used in veterinary medicine to
facilitate birth and to stimulate milk release.

36.  Relaxin hormone secreted by the Ovary brings out the
relaxation of the pelvic ligaments and enlargement of
Birth canal.
 During pregnancy progesterone and oestrogen bring
about the growth of mammary glands.
 Prolactin a hormone of Pituitary gland , influences the
mammary glands to secrete milk.
 Before birth , there is no secretion of milk because
Prolactin secretion is prevented by Progesterone and
Oestrogen.
 During birth , there is a sudden drop in the production of
these hormones and this permits the onset of Lactation

37. RELAXIN
OESTROGEN
OXYTOCIN
PROLACTIN
ENLARGEMENT OF
BIRTH CANAL
CONTRACTION OF
UTERINE MUSCLE
MILK SECRETION

38. CONCLUSION.
It is concluded that, the whole process of ovulation,
pregnancy and parturation, occurs under the
influence of hormones. Hormonal regulation play
important role in all these processes. Imbalance of
any one hormone out of all these hormones, can
affect the all these processes. Hormones are
regulated by pitutary gland of hypothalamus.
Releasing time of also important so that at particular
time the hormone level is same as it required for
complete process.

39. REFERENCE:
 Essential of Animal Physiology: By S.C RASTOGI
 Human Physiology: By C.C CHATERJEE.
 Animal Physiology: By P.S VERMA.
 INTERNET SOURCE.