1. Reproduction IB Biology (Core and Extension)

2. Copyright 2008 PresentationFx.com | Redistribution Prohibited | Image © 2008 clix/sxc.hu | This text section may be deleted for presentation.PresentationFx.com 6.6.1 Draw and label diagrams of the adult male and female reproductive systems.

3. Male & Female Differences Males produce sperm cells at a constant rate starting from sexual maturity Females are born with a set number of viable eggs & one is matured every 28 days after puberty the excretory system of the females does not cross the reproductive system like in males Females follow a complicated sexual cycle where one ovum matures approx. every 28 days

5. Male Reproductive System The Sperm’s Journey 1.Spermatogenesis in the testis 2.Maturation in the epididymis 3.Carried along vas deferens 4.Fructose for energy & protective mucus picked up at seminal vesicle 5.Prostate adds fluids to neutralise acid in the vagina 6.Ejaculation through the penis, via the urethra

10. The scrotum The sac that contains the testes Testes descend during the last 2 months of fetal development The temperature of the scrotum is a few degrees cooler than the body temperature Allows for sperm development If the testes do not descend the male will be sterile

11. Vas Deferens Carries sperm from the testes to the ejaculatory duct The ejaculatory duct is a tubule formed at the union of the vas deferens and the seminal vesicle ducts and opening into the urethra

12. Seminal Vesicles Mucous to protect sperm in vagina Some nutrients, including sugars for energy

17. 6.6.4 List three roles of testosterone in males

18. Functions of Testosterone Pre-natal development of male genitalia SRY gene on Y chromosome causes surge of testosterone in the male fetus. Causes penis and testes to develop Secondary sexual characteristics in puberty Increased aggression, muscle mass, pubic & body hair. Male grows taller & voice deepens Sperm production begins and male is able to procreate Sex drive and aggression Testosterone increases male sex drive and sperm production is constant for rest of life Aggression allows hunting and defense

19. Copyright 2008 PresentationFx.com | Redistribution Prohibited | Image © 2008 clix/sxc.hu | This text section may be deleted for presentation.PresentationFx.com Female Reproductive System Protecting the reproductive system is a real sperm-killer: Vagina is acidic, killing bacteria and sperm Tightly-closed cervix has a mucus plug, catching pathogens & sperm

22. 6.6.2 Outline the role of hormones in the menstrual cycle, including FSH (follicle stimulating hormone), LH (luteinizing hormone) estrogen and progesterone

23. Menstrual Cycle Puberty –Hormonal cycle About every 28 days To release an egg (ovum) –Possible fertilization Implantation into the inner lining of the uterus –Inner lining (endometrium) is rich with blood vessels –Lining breaks down if no implantation –Menstrual bleeding

25. Hormones from the brain Hypothalamus –Regulatory center of menstrual cycle Produces gonadotrophin releasing hormone –Targets the pituitary Pituitary reduces & secretes 2 hormones –Follicle stimulating hormone (FSH) –Luteinizing hormone (LH)

26. FSH – stimulate oocyte development LH – matures oocyte & causes release (ovulation) Pituitary Estrogen – develops endometrium; + feedback on FSH (more blood vessels) Progesterone – maintains endometrium – feedback on FSH and LH Ovaries Menstrual Cycle Hormones

27. Graafian follicles A spike in FSH & LH leads to ovulation –Release the oocyte from the Graafian follicle –Progesterone maintains the integrity of the endometrium

28. What next? No pregnancy Corpus luteum begins to break down Leads to a decline in both progeterone and estrogen levels Vascular endometrium canpt be maintained and blood vessels rupture and menstruation begins Pregnancy Progesterone levels remain high Embryo implants Negative feedback to hypothalamus –Does not produce GnRH –FSH & LH levels not conducive to the production of another Graafian follicle

29. Sex Hormones

34. 6.6.5 Outline the process of in-vitro fertilization (IVF)

35. In-vitro fertilization (IVF) Natural fertilization typically occurs in fallopian tubes 24-28 hours after ovulation Zygote begins to divide by mitosis and takes several more days to travel down the Fallopian tube Embryo reaches the endometrium and implants

36. Reasons for pregnancy problems Males with low sperm counts Males with impotence (failure to achieve or maintain an erection Females who cannot ovulate normally Females with blocked Fallopian tubes

37. Steps of an IVF procedure 1)After determining suitability for IVF, FSH and LH are given to stimulate multiple egg release 2)These eggs are collected 3)Eggs are fertilized with father’s sperm, in a dish, and incubated. This is “IVF”

38. Steps of an IVF procedure 4) After incubation, viable blastocysts are selected and developed into embryos. 5) Guidelines state that up to 3 embryos can be selected for implantation. Hopefully one or more will ‘take’. There is a risk of multiple pregnancy. 6) After bedrest & a month or so, a pregnancy test is administered. If positive, pregnancy continues as normal. If not, a woman may wait a few months and attempt another cycle

39. Steps to IVF

40. 6.6.6 Discuss the ethical issues associated with IVF

41. Arguments for IVF The right to have children Embryos that are visibly not healthy in early stages can be eliminated from consideration for implant Genetic screening is possible on embryos before implantation to eliminate the chance of passing on some genetic diseases Improving medical technology makes it safer than ever before Some governments cover costs Unused embryos can be stored & used later, donated or as a source of stem cells

42. Arguments against IVF Religion: is it playing God? The risk to the mother & fetuses of multiple pregnancies Extreme costs can be associated with IVF Emotional cost of failure can be high, especially with all the extra hormonal load Does termination of excess embryos count as ending a human life? Complex legal issues concerning the use of frozen embryos when couples split up

43. 11.4.1 Annotate a light micrograph of testis tissue to show the location and function of interstitial cells (Leydig cells), germinal epithelium cells, developing spermatozoa and Sertoli cells

44. Mature Sperm and Egg

48. 11.4.2 Outline the processes involved in spermatogenesis within the testis, including mitosis, cell growth, the 2 divisions of meiosis and cell differentiation

49. Spermatogenesis Production of male sperm in the testis Small and motile Produced throughout the life of a sexually mature male

50. Spermatogenesis

54. Important Definitions –Spermatogonia = sperm-producing cells found in the seminiferous tubules –Spermatocytes = a cell that arises from division of spermatogonia during spermatogenesis –Spermatid = an immature sperm cell that arises from division of a spermatocyte

55. Spermatogenesis Sertoli cell = a cell that provides metabolic and mechanical support to developing sperm cells, nourish the development of sperm cells until they are mature Epididymis = structures located along the posterior border of the testis, consisting of coiled tubules that store sperm cells, develops motility (swimming ability)

57. Spermatogenesis

58. 11.4.3 State the role of LH, testosterone and FSH in spermatogenesis

59. Hormonal control of spermatogenesis FSH is produced and releases by the anterior (frontal) pituitary and stimulates meiosis of the primary spermatocytes, giving secondary spermatocytes (now haploid).

60. Hormonal control of spermatogenesis LH is also produced & reaches the interstitial cells of the testis Stimulates testosterone production Testosterone stimulates the final meiotic division & differentiation of spermatids to form mature sperm cells

61. Semen Production

62. 11.4.4 Annotate a diagram of the ovary to show the location and function of germinal epithelium, primary follicles, mature follicle and secondary oocyte.

63. The Ovary Germinal epithelium – outer layer, produces primary follicles, constant cell division Primary follicles – location for development of oocyte Mature follicle – contains the oocyte, ready for ovulation