HORMONAL REGULATION OF OVULATION,PREGNANCY,PARTURITION

HORMONAL REGULATION OF OVULATION, PREGNANCY, PARTURITION.
M.Sc ZOOLOGY 4th SeM

1. Govt. Holkar Science College Indore(m.p.) Session: 2015 C.C.E-1 st 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).

4. 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:

5. 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

6. 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.

7. 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:

8. OESTROGEN O e strogen 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) L utenizing hormone. Oestrogen also stimulates the female reproductive organs to prepare for possible fertilization . This produces observable characteristics which can be monitored to determine fertility.

9. FUNCTIONS OF OESTROGEN Responsible for all the Puberty changes such as Growth of Uterus, Startification of v aginal 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.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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 .

15. 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 .

16. 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.

17. 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.

18. DURATION OF PREGNANCY. The Average duration of Human pregnancy is about 2 80 days(10Menstrual cycle). When calculated from the 1day of the last menstrual cycle. 266-270 when calculated from the time of Ovulation.

19. Duration of Gestation are shown in the following Table:

20. 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.

21. 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.

22. 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

23. 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.

24. 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.

25. 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 .

26. 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

27. OXYTOCIN HORMONE T he 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 .

28. 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.

29. 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. 

30. 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

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

32. 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.

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

34. Thank You