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1. Human Reproduction ♀ ♂ Padasalai Prepared by B. BALAJI., M.A.,M.Sc., M.Phil.,B.Ed., PG ASSISTANT IN BIOLOGY VIVEKANANDA VIDYALAYA MATRIC.HR.SEC.SCHOOL MADURANTAKAM

2. Both sexes have Reproductive organs called GENITALS or GENITALIA designed for the purpose of intercourse and conception.

4. Scrotum A sac-like pouch located behind the penis that holds each testes and helps regulate temperature for sperm production. Testicles or Testes The two testes are small organs that lie in the scrotum and produce sperm and the male hormone testosterone. The testicles are outside the body because the male sperm that is manufactured in the testes need cooler-than-body temperature for normal growth and development. Four to five billion sperm cells are produced each month.

5. Testoterone The male reproductive hormone made by the testicles which causes the changes of puberty. This hormone causes secondary sex characteristics, production of sperm and sexual urge. Sperm The microscopic cells produced by the male's testicles which can fertilize the female's ovum. They are tiny, living cells 100 times smaller than a pencil dot. (the smallest cell in a mans body ) It is destroyed by warm body temperature, acidic environment. It can survive in a women’s body for 5-8 days.

6. Epididymis The structure that forms a mass over the back and upper part of each testes. Sperm are stored there for as long as six weeks while they ripen to maturity. Cowpers Gland Two small pea-sized glands located beneath the prostate gland on both sides of the base of the penis. They secrete a clear, sticky fluid that helps to neutralize the acidity of the urethra. Vas Deferens two long, thin tubes that serve as a passageway for sperm and a place for sperm storage. The contraction of the vas deferens along with the action of the cilia help transport the sperm through the vas deferens.

7. Seminal Vesicles Two small glands that secrete a fluid that nourishes and enables the sperm to move. Prostate Gland surround the urethra beneath the bladder. The gland secretes an alkaline fluid that neutralizes the acid found in the male urethra and the female reproductive tract. Without the action of the secretions of the prostate gland, many sperm would die and fertilization of an ovum would be impossible. Urethra A dual purpose tube that both semen and urine pass through to leave the body. Semen and urine never mix.

8. Penis The male organ for sexual intercourse, reproduction, and urination. The reproductive purpose of the penis is to deposit semen in the vagina during sexual intercourse. SEMEN a combination of fluid that is produced in the seminal vesicles, prostate gland, and Cowper's gland. This fluid nourishes and helps sperm move through the urethra.

9. Female Reproductive System Female reproductive organs are for intercourse, reproduction, urination pregnancy and childbirth.

10. Front View

11. Ovary (Ovaries) • Two solid egg-shaped structures • They are attached to the uterus by ligaments. • Ovaries have two main functions. • Function • store and release the ova or female egg cell. Some of the ova disappear; others are dormant until each is ripened and released after puberty. • produce female sex hormones ESTROGEN and PROGESTERONE

12. Ovam • The female reproductive cell. • They are the largest cells in the female body. (about • the size of a grain of sand.) • The female baby is born with all the ova she will ever • have (about 200,000 in each ovary). • About 400-500 ova mature and are released over a • lifetime

13. Estrogen Estrogen is responsible for the secondary sex characteristics and the sex drive in females. It spurs the onset of puberty and is responsible for OVULATION Progesterone Progesterone builds up the lining of the uterus called the endometrium in preparation for the fertilized ovum Ovulation When the egg is released from the ovary. At the age of puberty The ovum moves to the surface of the ovary in bursts out The ova falls into the fallopian tube and waits for fertilization This happens every 28 days It happens at about the 14th day of the cycle

14. FALLOPIAN Two tubes attached on either side of the uterus. They are about four inches long and 3/16 inch in diameter (the size of a cooked spaghetti noodle). The oviducts carry egg cells toward the uterus and sperm cells toward the egg cell. Fertilization takes place in the upper third of the oviduct. Uterus A hollow, muscular organ (shaped somewhat like an upside-down pear, about the size of a fist). The uterus is lined with endometrium (a blood lining.) The uterus has one main function—to protect and nourish a fetus The walls of the uterus have the ability to stretch to the size of a small watermelon. After childbirth the uterus shrinks back to the original shape in 6-8 weeks, but it can take up to nine months for the uterus to fully recover.

15. Cervix The neck or opening of the uterus. A normal healthy cervix is the strongest muscle in the body. It dips down about half an inch into the vagina. It is normally plugged by mucus. It stays tightly closed during pregnancy, but thins and opens for the delivery of the baby. How big does it need to dilate to for birth? Vagina Female organ used for intercourse, it is an empty passageway leading from the vaginal opening to the uterus. It is only 3-4 inches long, but will lengthen during arousal. The vaginal walls are made of many small folds of membrane that stretch greatly to accommodate a baby during birth. The vaginal wall also secrete a fluid that helps to make intercourse easier.

16. Woman’s Cycle Day 1 – Menstruation begins (bleeding) Day 5 – Menstruation is usually ended Day 14 – Ovum has matured and bursts out of the ovary Day 15 – After 24 hours the egg is done Day 26 – In the absence of fertilization, estrogen/progesterone levels drop and the endometrium lining breaks down Day 28 – Menstruation begins again.

17. Mammary Glands • Modified sweat glands that produce milk (lactation) • Amount of adipose tissue determines size of breast • Milk-secreting mammary glands alveoli open by lactiferous • ducts at the nipple • Areola is pigmented area around nipple • Suspensory (Cooper’s) ligaments suspend breast from deep fascia of pectoral muscles

18. Physiology of the Breast • Milk production and secretion • Estrogens develop the ducts system in the breasts • Progestrone develop the milk-secreting glands which are called alveoli • Prolactin stimulate milk synthesis in the alveoli • Oxytocin stimulate milk ejection from the alveoli Physiology of Mammary Glands Continued • Milk ejection (release from glands) • Nursing stimulates the hypothalamus to produce oxytocin • Oxytocin secreted from the posterior pituitary • Oxytocin causes smooth muscles around alveoli to contract and squeeze milk into lactiferous ducts, lactiferous sinuses and into the nipple • Operated by positive feedback

19. Spermatogenesis Sperm forming cells go through two meiotic divisions • Each of four spermatids develop into a sperm • Second meiosis division give four spermatids,each with 23 single stranded chromosomes • First meiosis division give two secondary spermatocytes, each with 23 chromosomes that become double stranded. • Primary spermatocyte with 2n=46 chromosomes • Spermatogonium with 2n=46 chromosomes multiply by mitosis.

20. Sperm Morphology • Adapted for reaching and fertilizing the egg • Head contains DNA and the acrosome with enzymes for penetrating the egg • Midpiece contains mitochondria to form ATP for energy • Tail is flagellum used for locomotion

21. Oögenesis – Oögonia to Oöcytes • Germ cells from yolk sac migrate to ovary and • become potential egg cells called oögonia • In fetus, millions of oögonia produced by • mitosis but most of them degenerate (atresia) • Some develop into immature egg cells called • primary oöcytes during fetal development • 200,000 to 2 millions present at birth • 40,000 remain at puberty but only 400 mature during a woman’s reproductive life • Each month about 20 primary oöcytes become secondary oöcytes but usually only one survives to be ovulated from Graffian follicle

22. Oögenesis • Egg forming cells (oöcytes) go through two divisions • 1º = primary • 2º = secondary • Starts with a 2n=46 1ºoöcyte that divides, resulting in two n=23 cells, but one is a large 2º oöcyte and one is a small 1st polar body that may itself divide • Second division only occurs if 2º oöcyte is fertilized. Results in one large n=23 ovum (egg) and one small n=23 2nd polar body • Thus oögenesis results in one large fertilized egg (zygote) and possibly three small polar bodies

24. Female Reproductive Cycle • Controlled by monthly hormonal cycle from the hypothalamus, anterior pituitary and ovary • Monthly cycle of changes in ovary and uterus • Ovarian cycle • Changes in ovary during and after maturation of the follicle and oocyte • Uterine cycle (menstrual cycle) • Preparation of the uterus to receive fertilized ovum • If implantation does not occur, the functional layer of endometrium is shed during menstruation

25. Hormonal Regulation of Reproductive Cycle • Gonadotropin Releasing Hormone (GnRH), secreted by the hypothalamus, controls the female reproductive cycle • Stimulates anterior pituitary to secrete Follicle Stimulating Hormone (FSH) & Luteinizing Hormone (LH) • FSH & LH target the ovaries and drive the ovarian cycle (monthly changes in the ovary) • Estrogens and progesterone from the ovaries drive the uterine cycle (monthly changes in the uterus)

26. Phases of Ovarian Cycle • Follicular Phase • FSH from anterior pituitary stimulates follicle growth • Follicles grow into Graafian (mature) follicle • Granulosa cells of follicle secrete estrogens and inhibin • Increasing levels of estrogens and inhibin inhibit FSH • Increasing estrogens also stimulates secretion of LH • Ovulation • LH stimulates rupture of the Graafian follicle and release of oöcyte from ovary into the pelvic cavity • Fimbriae of Fallopian tube picks up the ovulated oöcyte

27. Phase of Ovarian Cycle • Luteal phase (postovulatory phase) • LH stimulates development of Corpus luteum from ovulated or ruptured follicle • Corpus luteum secretes mostly progesterone & some estrogens • Progesterone prepares endometrium for possible pregnancy Follicular Phase Ovulation Luteal Phase

28. Phases of Uterine Cycle • Proliferative phase • Rising estrogen levels from the growing follicle stimulates growth of the functional layer of endometrium to 4-10 mm thickness • Secretory phase • Corpus luteum of ovary secretes progesterone • Progesterone stimulates • Increased thickening of the functional layer of endometrium to 12-18 mm • Increased blood supply into the endometrium • Growth of endometrial glands and secretion of uterine milk

29. Phase of Uterine Cycle • Menstruation phase (menses) • Decline in progesterone levels causes functional layer of endometrium to discharge resulting in vaginal bleeding called menstruation • Mark the beginning of the next cycle

30. Summary of Ovarian and Menstrual Cycles

31. Menopause Menopause is the phase in a women’s life when ovulation and menstruation stops. The average age of menopause is 45-50 years. It indicates the permanent cessation of the primary functions of the ovaries.

32. FERTILISATION AND IMPLANTATION

33. Structure of ovum

34. FERTILIZATION It is the process during which a male gamete (sperm) unites with a female gamete (oocyte) to form a single cell (ZYGOTE).

35. Fertilization • Begins with a contact between the sperm & the ovum. • Ends up with interminglingof the maternal and paternal chromosomes.

36. Phases of Fertilization • 1- Passage of sperm through corona radiata, under the effect of : hyaluronidase enzyme from sperms, tubal E. and movement of tail of sperm. • 2- Penetration of the zonapellucida by head of sperms through acrosine E. from acrosomeof one sperm. • 3- Fusion of the plasma membrane of the oocyte and that of the sperm. so sperm’s plasma membrane remains behind.

37. Morula • The smaller cells are called Blastomeres. • there are 12-32 blastomeres the developing human is called MORULA. • The Morula reaches the uterine cavity at this stage. • Spherical Morulais formed about 3 days after fertilization.

38. Formation of blastocyst : • The Morula reaches the uterine cavity by the 4thday after fertilization, & remains free for one or two days. Fluid passes from uterine cavity to the Morula. • Now the Morula is called Blastocyst, its cavity is called blastocystic cavity, its cells divided into Embryoblast & Trophoblast.

39. IMPLANTATION • Definition : • It is the process by which the Blastocystpenetrates the superficial(Compact) layer of the endometrium of the uterus. • Site: • The normal site of implantation is the posterior wall of the uterus near the fundus. • Time: • It begins about the 6th day after fertilization. • It is completed by the 11th or 12th day. 6th day

40. By the 5th daythe Zona pellucidadegenerates. Blastocyst beginsimplantationby the 6th day. Trophoblast cells penetrate the epithelium of the endometrium. Penetration results from proteolytic enzymes (eg.COX-2) produced by the trophoblast. 6th day 7th day

41. Ectopic Pregnancy Ectopic Pregnancy: 1- Placenta Previa. 2- Tubal. 3- Ovarian. 4- Abdominal. 5- Pelvic. 6- Cervical. Placenta previa centralis • It meansimplantation outside the uterus. • 95 to 97% of ectopic pregnancies occurs in the uterine tube. • Most are in the ampulla & isthmus. • Placenta previa : • Implantation occurs in the lower uterine segment. Placenta previalateralis Placenta previamarginalis

42. Maintenance of pregnancy and embryonic development • The inner cell mass in the blastula is differentiated into epiblast and hypoblast immediately after implantation. • The extra embryonic membranes namely the amnion, yolk sac, allantois and chorion protect the embryo from dessication, mechanical shock and help in the absorption of nutrients and exchange of gases

43. The chorionic villi and the uterine tissues form the disc-shaped placenta. • Placenta is a temporary endocrine organ formed during pregnancy and it connects the foetus to the uterine wall through the umbilical cord • Human pregnancy lasts for about 280 days or 40 weeks and is called the gestation period. It can be divided for convenience into three trimesters of three months each.

44. The first trimester is the main period of organogenesis 4 Weeks

45. Two Months

46. 8 Weeks 6 Weeks 7 Weeks

47. 3 Months

48. 4th MONTH

49. 18 WEEK 15 WEEK 16 WEEK

50. 6 Months