1. Hormonal cycles: fertilization and early development
Dr. Areefa Albahri
Midwifery department

2. Introduction
Monthly physiological changes take place in the ovaries and the uterus, regulated by hormones produced by the hypothalamus, pituitary gland and ovaries. These cycles commence at puberty and occur simultaneously and together are known as the female reproductive cycle.
The functions of the cycle are to prepare the egg often referred to as the gamete or oocyte for fertilization by the spermatozoon (sperm), and to prepare the uterus to receive and nourish the fertilized egg. If fertilization has not taken place the inner lining of the uterus or endometrium and the egg are shed and bleeding occurs per vagina, and the cyclic events begin again.

3. The first-ever occurrence of cyclic events is termed menarche, meaning the first menstrual bleeding. The average age of menarche is 12 years, although between the ages 8 and 16 is considered normal. Factors such as heredity, diet and overall health can accelerate or delay menarche. Interference with the hormonal-organ relationship during the reproductive years is likely to cause menstrual cycle dysfunction which may result in failure to ovulate.

4. The cessation of cyclic events is referred to as the menopause, and signifies the end of reproductive life. Each woman has an individual reproductive cycle that varies in length, although the average cycle is normally 28 days long, and recurs regularly from puberty to the menopause except when pregnancy intervenes

7. Ovarian Cycle
The ovarian cycle consist of two phases all phases work under control of hormones
Phase I
The follicular phase
Formation of oogenia in the germinal epithelium of the ovary known as oogenesis. The preimordial germs cell differentiate into oogenia in the ovary during fetal life.
Some germ cell develop into primary oocyte and enter the prophase of meiosis I cell division. Further meiosis and secondary oocyte will not develop until fertilization occurs.
The follicular phase
The formation of oogonia in the germinal epithelium of the ovaries is known as oogenesis. Primordial germ cells differentiate into oogonia in the ovaries during fetal life. These diploid stem cells divide mitotically and proliferate into millions of germ cells. Most of the germ cells degenerate (by atresia), however some develop further into primary oocytes, and enter the prophase of meiosis I cell division. Meiotic arrest occurs and the process does not continue until aher puberty (further meiotic division takes place at ovulation of the secondary oocyte and the process is only completed if fertilization occurs).Whilst in this arrested prophase stage of meiosis I the primary oocyte is surrounded by follicular cells and is hence known as the primordial follicle. There are up to 2 million primary oocytes in each ovary at birth and due to atresia the number is reduced to approximately at puberty; 400 of these will mature and ovulate during the woman's lifetime (Tortora and Derrickson 2011). Following puberty FSH and LH further stimulate the development of primordial follicles into primary and secondary follicles and subsequently into large preovulatory or Graafian follicles (Fig. 5.3) by a process known as folliculogenesis.

10. How much the female ovary contains of oocytes?
The fetus female ovary contain up to 2 million primary oocytes in each ovary at birth and due to atresia the number decrease to approximately 40,000 at puberty 400 of these will mature and ovulate during woman lifetime.

11. 1. Hypothalamus releases GnRH 2
1. Hypothalamus releases GnRH 2. Release of GnRH triggers anterior pituitary gland to release FSH and LH
FSH- responsible for the maturation of ovum and follicle formation.
Causes an increase in estrogen
LH – triggers ovulation and growth of uterine lining

12. Graafian follicle undergoes cell division (mitosis, meiosis)
FSH activates primordial follicles to mature.
Primordial follicles start producing follicular fluid that is HIGH IN ESTROGEN (estradiol) and some progesterone
primordial follicles propelled toward the surface of ovary and is now called Graafian Follicle.
Graafian follicle undergoes cell division (mitosis, meiosis)
GF divides into:
.a primary oocyte – with more cytoplasm
secondary oocyte – with less cytoplasm
GF after meiosis contain haploid cells (23 chromosomes)

13. Upsurge in LH causes the release of prostaglandin
Prostaglandin causes the rupture of GF releasing ovum and follicular
Increase in LH causes production of Lutein (bright yellow fluid, High in Progesterone)
Follicle becomes “Corpus luteum”

14. Ovulation is the process whereby the dominant graafian follicle ruptures & discharges the secondary oocyte into the pelvic cavity.
High estrogen level cause sudden surge in LH around the day of 28 day cycle, which last for approximately 48 hours.

15. Phase II The luteal phase
This is the process by which the cell of rupture follicle proliferate and form the yellow body known as corpus luteum. This corpus luteum produce estrogen, relaxin, progesterone for 2 weeks to develop the endometrium.

16. The menstrual cycle is measured from the first day of menstrual bleeding, Day 1, up to Day 1 of your next menstrual bleeding. Although 28 days is the average cycle length, it is normal to have a cycle that is shorter or longer.
Most of menstrual period last from 3- 6 days most of the blood loss happens during the first 3 days. This is also when you might have cramping pain in your pelvis, legs, and back. Cramps can range from mild to severe. The cramping is your uterus contracting, helping the endometrium shed. In general, any premenstrual symptoms that you've felt before your period will go away during these first days of your cycle.

17. Answer the following question
Immature egg cells are called ________.
Oocyte
Mature egg called
Ova
corpus luteum doesnot produce which
relaxin
prostaglandin
Which hormone cause the rupture of GF releasing ovum and follicular
Prostaglandin
Which hormone triggers ovulation and growth of uterine lining LH

18. Physiology of menstruation
1st PHASE: proliferative
High levels of oestrogen causes thickening and proliferation of endometrium
LH is increased, Oestrogen is increased

19. 2nd PHASE: Secretory
Increased levels of progesterone causes glands at endometrium to become rich & dilated with quantities of glycogen and other nutrient substances.
Increased in capillaries making endometrium appear like a rich spongy velvet
Decreased LH, Increased Progesterone

20. Capillaries rupture, endometrium sloughs off
3RD PHASE: ISCHEMIC
Decreased estrogen and progesterone levels causes the degeneration of the endometrium.
Capillaries rupture, endometrium sloughs off
4th phase: menses/menstrual flow
menses is composed of:
Blood from the ruptured capillaries
Mucin from glands
Fragments of endometrial tissue
Microscopic, atrophied, unfertilized ovum
Total blood loss: 30-80ml
Iron loss: 11mg
Mucin =protein produced by epithelial tissue

21. 1st half of the cycle
Hormones decreased
Mucus thick and scanty
Poor sperm survival
Ovulation
Estrogen is increased
Cervical mucus thin and copious
Excellent sperm survival
2nd half
Decreased progesterone level
Mucus is thick

22. Fertilization
Contact of sperm & secondary oocyte occurs in uterine tube
Sperm penetration
Oocyte completes meiosis II
Nuclear fusion
Fertilization.ppt

23. Fertilization
Sperm penetration
Why so many?
Fertilization.ppt

24. Fertilization Oocyte completes meiosis II Nuclear fusion
Fertilization.ppt

25. Early Development
Cleavage in uterine tube
Fertilization.ppt

26. Early Development Implantation 6-7 days after fertilization
Trophoblast forms placenta
“Inner cell mass” forms embryo
Fertilization.ppt

27. Early Development Implantation Trophoblast forms placenta
“Inner cell mass” forms embryo
Fertilization.ppt

28. Early Development Placenta
Provides large area for exchange of O2, CO2, nutrients, metabolic wastes between fetal and maternal blood
Fertilization.ppt

29. Pregnancy Pregnancy lasts 39-40 weeks, Hormonal changes
280 days from last menstrual period
3 trimesters
Hormonal changes
Fertilization.ppt

30. Thank you 