1. The Reproductive System and Development Chapter 25 – Lecture Notes
to accompany
Anatomy and Physiology: From Science to Life
textbook by
Gail Jenkins, Christopher Kemnitz, Gerard Tortora

2. Chapter Overview 25.1 Sperm Production 25.2 Male Reproductive System
25.3 Female Reproductive System
25.4 Vagina and Mammary Glands
25.5 Ovarian and Uterine Cycle
25.6 Implantation of Blastocyst
25.7 Embryonic to Fetal Period

3. Chapter Overview 25.8 Maternal Changes During Pregnancy 25.9 Labor
25.10 Milk Production and Ejection

4. Essential Terms gamete germ cells with haploid number of chromosomes
fertilization
occurs when sperm unites with secondary oocyte
pregnancy
sequence of events resulting in birth of child
gonads
male testes and female ovaries which secrete hormones and produce gametes

5. Introduction Sexual Reproduction
Males and females differ anatomically to produce gametes and support a fetus
Fertilization is the result of male and female gametes joining
Pregnancy begins with fertilization and usually results in birth of a child
Gonads produce gametes and hormones

6. Concept 25.1 Sperm Production

7. Male Reproductive System
Testes – System of Ducts
Epididymis, ductus deferens, ejaculatory ducts, and urethra
Accessory glands
Seminal vesicles, prostate, and bulbourethral glands
Supporting Structures
Scrotum and penis

8. Figure 25.1a

9. Figure 25.1b

10. Scrotum
Scrotal location and muscle contraction regulate temperature of testes
Normal sperm production occurs 2-3°C lower than core body temperature
Response to cool temperatures
Cremaster muscles contract to pull testes close to body
Dartos muscles contract to tighten scrotum
Response to warm temperatures
Reverse of above actions

11. Figure 25.2

12. Testes One testes in each sac of scrotum
Descend during seventh month of fetal development
Tunica albuginea is located deep to tunica vaginalis and forms lobules
Lobules contain seminiferous tubules
Spermatogenesis carried out by seminiferous tubules of testes

13. Figure 25.3a

14. Figure 25.3b

15. Figure 25.3c

16. Testes Spermatogenic cells Sertoli or sustentacular cells
Begin sperm production at puberty
Sertoli or sustentacular cells
Junctions form blood-testis barrier
Nourish spermatogenic cells
Carry out phagocytosis
Control spermatogenic movement
Produce fluid for transport
Secrete hormone inhibin
Leydig (interstitial) cells
Secrete testosterone

17. Figure 25.4a

18. Figure 25.4b

19. Spermatogenesis
Begins with spermatogonia and diploid number of chromosomes
Some pass through blood-testis barrier
Primary spermatocytes also diploid

20. Figure 25.5

21. Spermatogenesis Meiosis I Meiosis II Crossing-over during metaphase I
Secondary spermatocytes result
Each with haploid number
Meiosis II
Results in four spermatids

22. Spermatogenesis Cytoplasmic bridges link the four daughter cells
Spermiogenesis
Transformation of spherical spermatids into elongated sperm
Formation of arcosome
Flagellum develop
Mitochondria multiply

23. Sperm 300 million per day produced
Survive 48 hours in female reproductive tract
Sperm Parts
Head
Nucleus
Arcosome
Tail
Neck
Middle piece
Principal piece
End piece

24. Figure 25.6

25. Hormonal Control of Testes
Negative feedback loops control testosterone release and spermatogenesis
Gonadotropin-releasing Hormone (GnRH)
Increased production at puberty
Stimulates secretion of LH and FSH
Luteinizing hormone (LH)
Stimulates Leydig cells
Follicle-stimulating hormone (FSH)
Stimulates Sertoli cells to secrete ABP

26. Figure 25.7

27. Hormonal Control of Testes
Testosterone
Principal androgen
Synthesized from cholesterol
Suppresses LH and GnRH secretion
Converted to DHT in prostate and seminal vesicles
Dihydrotestosterone (DHT)
Stimulates development of external genitals
Androgen-binding Protein (ABP)
Binds to and keeps testosterone levels high
Inhibin
Inhibits FSH secretion

28. Effects of Testosterone and Dihydrotestosterone
Prenatal development
Development of male sexual characteristics
Development of sexual function
Stimulation of anabolism

29. Figure 25.8

30. Concept 25.2 Male Reproductive System

31. Reproductive System Ducts in Males
Ducts of testis
Seminiferous tubules
Straight tubules
Rete testis
Efferent ducts
Ductus epididymis
Epididymis
Site of sperm maturation and storage
Consists of ductus epididymis
Head – superior portion formed by efferent ducts of testis
Body
Tail – continues as ductus (vas) deferens

32. Ductus Deferens Terminal portion is the ampulla
Conveys sperm from epididymis toward urethra
Storage and reabsorption of sperm

33. Figure 25.9

34. Spermatic Cord Supporting structure ascends out of scrotum
Comprised of several structures
Ductus deferens
Testicular artery
Pampiniform plexus
Autonomic nerves
Lymphatic vessels
Cremaster muscles

35. Ejaculatory Ducts
Formed by duct of seminal vesicle and ampulla of ductus deferens
Eject sperm and seminal vesicle secretions from urethra to exterior

36. Urethra Shared by reproductive and urinary systems 3 subdivisions
Prostatic urethra
Membranous urethra
Spongy (penile) urethra

37. Accessory Sex Glands
Produce fluids to protect semen and facilitate their movement
Seminal vesicles
Prostate
Bulbourethral or Cowper’s glands

38. Seminal Vesicles Alkaline fluid Fructose Prostaglandins
Clotting proteins
Approximately 60% of semen volume

39. Prostate Gland Citric acid
Proteolytic enzymes – prostate-specific antigen (PSA)
Pepsinogen
Lysozyme
Amylase
Hyaluronidse
Milky, acidic fluid (pH ~ 6.5)
Approximately 25% semen volume

40. Bulbourethral / Cowper’s Glands
Pea sized glands active during sexual arousal
Alkaline fluid
Secrete lubricating mucus

41. Semen Combination of sperm and seminal fluid
2.5 – 5 mL per ejaculation
50 – 150 million sperm/ml
Alkaline pH ~ 7.2 – 7.7
Seminalplasmin – antibiotic

42. Penis Contains urethra Passage for sperm and urine 3 Parts
Root
Body
Glans penis
Erection maintained by parasympathetic fibers
Ejaculation, a sympathetic reflex, releases semen to exterior

43. Figure 25.10a

44. Figure 25.10b

45. Concept 25.3 Female Reproductive System

46. Figure 25.11a

47. Figure 25.11b

48. Figure 25.12

49. Figure 25.13

50. Figure 25.14a

51. Figure 25.14b

52. Figure 25.15

53. Concept 25.4 Vagina and Mammary Glands

54. Concept 25.5 Ovarian and Uterine Cycle

55. Concept 25.6 Implantation of Blastocyst in Endometrium

56. Concept 25.7 Embryonic to Fetal Period

57. Concept 25.8 Maternal Changes During Pregnancy

58. Concept Labor

59. Concept 25.10 Milk Production and Ejection