1. Biology 30 Unit 2 Reproduction and Development

2. Biology 30 Unit 1 Introduction We will be learning about the following topics: Structure/function of male/female reproductive systems Hormonal control of male/female reproductive cycles Birth control methods Causes of infertility/reproductive technologies Process of fertilization and development

3. Biology 30 Reproductive System Why is reproduction so important? Ensures the survival of a species What is reproduction? Union of a male and female sex cell to form new genetic combinations Survival of species depends on the varied offspring

4. Biology 30 The Importance of Reproduction Continuation of the species Creation of diversity within the species Adaptation Change Mutation Survival of the fittest

5. Biology 30 Types of Reproduction Sexual Sex cells from a male and a female fuse to form a new organism Involves meiosis (formation of gametes ) Asexual Organism make a copy of itself Only one “parent” involved No meiosis Occurs in prokaryotic cells and some plants via vegetative reproduction

6. Biology 30 The Reproductive System Gonads: organs that produce gametes and hormones Ducts: receive and transport gametes Accessory glands: secrete fluids into ducts Perineal structures: collectively known as external genitalia

7. Biology 30 Basic Human Reproduction Separate male and female systems Male gonads called testes produce sperm cells Sperm production begins at puberty and continues into old age Approximately 1 billion produced each day Female gonads called ovaries produce ova (ovum, sing.) Ova are larger than sperm Female generally releases one ovum every 28 days following onset of menstruation and continuing to menopause Ova are developed prior to birth, approximately (400,000) Sperm cell fertilizes an ovum in the oviducts of the female to form a zygote which implants (attaches) to the uterine wall where it grows and develops

8. Biology 30 Development of the Male Reproductive System Development of male reproductive begins at 12 th week of embryonic development Prior to this male and female embryos are similar Testes descend into the scrotum during week 30-32 of male embryonic development Scrotum is a sac-like pouch of skin that contains the testes and is locates below the pelvic region and outside of the body. Scrotum is 92º F (33º C) while normal body temperature is 98.6º F (37º C) Sperm production is optimal at this lower temperature

9. Biology 30 Problems with testis descent

10. Biology 30 Basic Anatomy - Testes Testes Normally two Housed in the scrotum Produce sperm cells Tube called the vas deferens carries sperm cells to the urethra for ejaculation Two main cell types Seminiferous cells – produce sperm (site of meiosis) Interstitial cells – produce testosterone

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12. Basic Anatomy - Penis Male sexual organ and external organ of urination No erectile bone – erection achieved by engorgement of spongy erectile tissue chambers Corpus cavernosa (2) Corpus spongiosum (1) forms glans penis (tip) Stimulation of erectile tissue due to parasympathetic nervous system Arteries leading to penis dilate Veins leaving the penis constrict due to pressure from arteries and enlarged spongy tissue Stimulation due to sexual arousal or other factors – full bladder, friction, dreams, etc.

13. Biology 30 The Male Reproductive System

14. Biology 30 Male Reproductive System

15. Biology 30 Functions of structures Scrotum – pouch of skin that stores testes located below pelvic region Vas Deferens – carries sperm from testes to urethra Semen – fluid that contains sperm and other chemicals Sertoli cell – nourishes developing sperm cells Seminiferous tubules – found in each testis where sperm cells develop

16. Biology 30 Functions of Structures…cont’d Epididymus – coiled tube located on each testis where sperm cells mature Seminal vesicles – contain substances to help sperm survive (fructose and prostaglandins) Prostate gland – contains a substance to protect sperm cells in vagina Cowper’s Gland – secretes mucous rich fluids prior to ejaculation Urethra – expels both semen and urine from penis (but never at the same time)

17. Biology 30 Sperm Cells and Spermatogenesis Formed in the testicles Nucleus contains 23 chromosomes Half carry a Y chromosome and half carry an X chromosome Reduced cytoplasm = reduced energy store Mitochondria surrounds flagellum Acrosome at tip contains enzymes to aid penetration of ovum Sertoli cells nurture developing sperm Spermatogonia (46 chromosomes) Spermatocytes (23 chromosomes) Sperm cells meiosis 9-10 days epididymis

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19. Spermatogenesis

21. Sperm Cells – Interesting Facts Can live 1-3 hours outside the body depending on temperature, moisture, etc. Can live 5-7 days in the cervix Up to 500 million sperm cells per ejaculation. Below 40 M is considered infertile Average ejaculation is 1 teaspoon (5 ml) in volume Can be stored for many years in cryogenic storage systems Used in artificial insemination Tadpole like shape Head, mid-piece, and tail Fertility rates depend on number and motility

22. Biology 30 Seminal Fluid Secretions from three glands make up seminal fluid Seminal vesicle secretions (60%) Fructose Prostagladins Prostate secretions (30%) Alkaline buffer (basic) Cowper’s gland (bulbourethral gland) Pre-ejaculatory fluid

23. Biology 30 Hormonal Control of the Male Reproductive System

24. Biology 30 Topics - Hormonal Control of the Male Reproductive System Where testosterone is produced Functions of testosterone Structures that control the production of sperm and testosterone Hormones involved in the control of production of sperm and testosterone Describe how production is regulated (negative feedback system) to maintain homeostasis of testosterone

25. Biology 30 Where Testosterone is Produced In interstitial cells in testes

26. Biology 30 Functions of Testosterone Stimulates spermatogenesis (production of new sperm cells) Promotes development of secondary sex characteristics Maturation of testes and penis Increase in sex drive Facial/body hair Growth of larnyx (deepening of voice) Secretion of body oils (acne)

27. Biology 30 Structures that control the production of sperm and testosterone Hypothalamus and Pituitary Gland

28. Biology 30 Hormonal Control of Male Reproductive System GnRH ( Gonadotropin-releasing hormone ) produced in hypothalamus At the pituitary, GnRH stimulates the synthesis and secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) FSH stimulates production of sperm cells in seminiferous tubules of testes LH stimulates production of testosterone by interstitial cells (Leydig cells) of testes Negative FB Loop: The hypothalamus detects high levels of testosterone which lowers GnRH production in the pituitary which in turn lowers LH secretions. This results in lower levels of testosterone production.

29. Biology 30 Hormones Involved… In the production of sperm: Follicle Stimulating Hormone (FSH) Acts on the Sertoli Cells in the testes (seminti to produce sperm cells In the production of testosterone: Luteinizing Hormone (LH) Acts on the interstitial cells in the testes to produce testosterone

30. Biology 30 Negative Feedback Control Required to maintain constant levels of testosterone and sperm Hypothalamus → GnRH → Pituitary → LH → Interstitial cells → testosterone produced Hypothalamus → GnRH → Pituitary → FSH → Sertoli Cells → Sperm produced If sperm/testosterone too high → system shuts off to decrease levels set level If sperm/testosterone is too low → system turns on to increase levels to set level

31. Biology 30 Hormonal Feedback/ Regulation of Male Reproductive Function

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33. Female Reproductive System

34. Biology 30 Female Reproductive System Development Development of female reproductive begins at 12 th week of embryonic development Prior to this male and female embryos are similar Paired ovaries form near the kidneys during embryonic development and remain in the abdominal region Ovaries contain ova, or “eggs” Ovaries also produce female sex hormones Estrogen Progesterone

35. Biology 30 Female Reproductive System Internal (X-Section)

36. Biology 30 Female Reproductive System - External Anatomy Separate openings to the outside for products of the urinary and reproductive systems Urethra Vagina Clitoris develops from the same embryonic tissue as the penis and consists of erectile tissue

37. Biology 30 Basic Anatomy - Female Reproductive System 10-12 cm in length oviducts, or Fallopian tubes, connect ovaries to the uterus Released ovum travels along oviducts via cilia Fertilization of ovum occurs in oviduct Oviducts join at uterus, or womb Uterus is connected to vagina by the cervix

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39. The Uterus Composed of three main tissues: 1. Perimetrium – fibrous elastic tissue that surrounds the uterus and holds it place with ligaments 2. Myometrium – muscular lining that supports a fetus and also contracts during child birth 3. Endometrium – forms the placenta for the developing fetus. Released if no fertilization takes place – menstruation.

40. Biology 30 Main Structures and Functions The ovaries produce the cells that become ova (eggs). A released oocyte moves into the oviduct (or Fallopian tube) where it may be fertilized if sperm are present. If fertilized, it completes meiosis and becomes an ovum. If an embryo results it will attach to the lining of the uterus to complete its development. The cervix is the opening from the uterus into the vagina. Holds fetus in place during pregnancy. The vagina is the canal for entry of the penis and exit of menstrual flow and serves as the birth canal.

41. Biology 30 Ovaries Each ovary contains hundreds of thousands of follicles Follicles are the structure in the ovaries that produces the eggs and, in particular, the female sex hormones, estrogen and progesterone Each follicle contains an oocyte An oocyte is a cell that has begun the process of meiosis and can eventually produce an ovum (egg) FSH and LH from the anterior pituitary create changes in the ovary during various phases of the ovarian cycle

42. Biology 30 Follicles Primary follicles consist of a primary oocyte surrounded by granulosa cells Outer layer of connective tissue surrounding the follicles is called the theca Theca secretes androgens that are converted to estrogen in the granulosa cells Secondary follicles secrete estrogen and nurture the secondary oocyte Eventually forms an ovarian follicle (Graafian follicle) that ruptures and releases the ovum

43. Biology 30 Follicle Stages in the Ovary

44. Biology 30 Hormones and the Ovary FSH causes development of the follicle during the first half of the menstrual cycle After ovulation the follicle becomes the corpus luteum under the influence of LH Negative feedback regulates hormone levels

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46. Uterine (Menstrual) Cycle Day 1-5: Menstruation - shedding of uterine lining - due to low hormone levels Day 6-13: Proliferative Phase -FSH stimulates follicle which in turn secretes estrogen. Estrogen causes the endometrium to thicken. Day 14: Ovulation Day 15-28: Secretory Phase – LH promotes the formation of the corpus luteum within the ruptured follicle - which in turn produces progesterone, which in turn stimulates the endometrium to secrete thick nutrient-rich fluids (ready for implantation). If no implantation then the corpus luteum degenerates as LH levels fall. Progesterone levels also fall and endometrium is no longer maintained – menses begins and cycle repeats.

47. Biology 30 No Fertilization LH levels fall during the luteal phase Corpus luteum degenerates Progesterone levels fall Uterine lining (endometrium) is no longer maintained due to low levels of progesterone

48. Biology 30 Fertilization Fertilization occurs in the upper portion of the oviduct and implantation occurs on the uterine wall Embryonic cell divisions begin and the embryo produces the hormone HCG HCG maintains the corpus luteum so that progesterone continues to be released Uterine lining continues to thicken so the embryo can survive HCG → human chorionic gonadotropin

49. Biology 30 Critical Hormones in Reproduction FSH FSH - secreted by the anterior pituitary. Stimulates the development of an ovarian follicle in a female or the production of sperm in a male. LH LH - produced by the anterior pituitary gland. Stmulates the development of the corpus luteum in females and the production of testosterone in males. Estrogen Estrogen - Female sex hormone, which, along with progesterone, maintains the primary sex organs and stimulates development of the female secondary sex characteristics. Progesterone Progesterone -Female sex hormone secreted by the corpus luteum of the ovary and by the placenta.

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52. Reproductive Health Issues Fibroid Tumors Ovarian and Cervical Cancer Bartholin Cysts

53. Biology 30 Fibroid Tumors

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55. Ovarian Cancer

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57. Resources Female Reproduction