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Chapter 26b

Chapter 26b. Reproduction and Development. Male Reproductive Structures. External genitalia Penis and scrotum Common passageway Urethra Accessory glands and ducts Prostate gland Seminal vesicle Bulbourethral gland. Male Reproductive Structures - Overview. Figure 26-8 (1 of 2).

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Chapter 26b

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  1. Chapter 26b Reproduction and Development

  2. Male Reproductive Structures • External genitalia • Penis and scrotum • Common passageway • Urethra • Accessory glands and ducts • Prostate gland • Seminal vesicle • Bulbourethral gland

  3. Male Reproductive Structures - Overview Figure 26-8 (1 of 2)

  4. Male Reproductive Structures - Erectile Tissues Figure 26-8 (2 of 2)

  5. Male Reproductive Structures • Testes (sperm production) • Seminiferous tubules • Epididymis (sperm maturation) • Vas deferens (aka “ductus deferens”, a passageway into abdomen and delivery to the urethra)

  6. Male Reproductive Structures - Sagittal View ANATOMY SUMMARY THE MALE REPRODUCTIVE SYSTEM Ureter Urinary bladder Pubic symphysis Seminal vesicle Vas deferens Rectum Ejaculatory duct Prostate gland Urethra Bulbourethral gland Penis Epididymis Testis Scrotum (a) Figure 26-9a

  7. Male Reproductive Structures - Scrotal Structures ANATOMY SUMMARY THE MALE REPRODUCTIVE SYSTEM Head of epididymis Seminiferous tubule Epididymis Vas deferens (b) Scrotal cavity Figure 26-9b

  8. Seminiferous Tubule - Cross-Section ANATOMY SUMMARY THE MALE REPRODUCTIVE SYSTEM Capillary Sertoli cell Leydig cell Spermatogonium (c) Figure 26-9c

  9. Spermatogenesis in the Testes • Seminiferous tubules • Sertoli cells surround and support developing sperm • Spermatogonia divide and produce all sperm cells • Primary and secondary spermatocytes • Spermatids • Spermatozoa • Interstitial tissues support spermatogenesis • Leydig cells  testosterone • Capillaries deliver nutrients and remove wastes

  10. Seminiferous Tubule - Detail ANATOMY SUMMARY THE MALE REPRODUCTIVE SYSTEM Lumen of seminiferous tubule Spermatids Spermatozoa Secondary spermatocyte Sertoli cells Primary spermatocyte Spermatogonium Tight junction between Sertoli cells Basal lamina Fibroblast Capillary Leydig cells (d) Figure 26-9d

  11. Spermatozoa Structure Acrosomecontainsenzymes Head Mid piece Nucleus Centrioles Mitochondrialspiral Tail(flagellum) Microtubules Figure 26-10

  12. Regulation of Spermatogenesis • Hormones control the production of sperm • GnRH stimulates the release of LH and FSH • LH Leydig cells testosterone • FSH Sertoli cells cell products

  13. Regulation of Spermatogenesis GnRH Hypothalamus Anteriorpituitary FSH LH Leydigcells Spermatogonium Inhibin Testosterone (T) Spermatocyte Testes Sertolicell Secondmessenger To bodyfor secondaryeffects Cellproducts Sertolicell Androgen-bindingprotein (ABP) ABP T Figure 26-11

  14. Accessory Glands Contribute to Semen • Accessory glands contribute 99% of semen volume, as well as the following • Seminal vesicles– fructose, vitamin C, prostaglandins • Prostate gland – buffers, citric acid, enzymes • Bulbourethralgland – mucus, buffers

  15. Accessory Glands Contribute to Semen Table 26-3

  16. Female Reproductive System • Female reproduction is a cyclic process • Hormones from the hypothalamus and anterior pituitary stimulate the ovaries • The ovaries release estrogen and progesterone in varying patterns during each cycle • Ovulation releases a mature oocyte monthly • Estrogen and progesterone prepare the uterus for possible pregnancy

  17. Female Reproductive Structures • External genitalia (aka vulva, or pudendum) • Labia majora • Labia minora • Clitoris • Vagina • Hymen • Urethral opening is inside the labia minora

  18. Female Structures - External Genitalia ANATOMY SUMMARY THE FEMALE REPRODUCTIVE SYSTEM Clitoris Urethral opening Labium minora Vagina Labium majora Hymen (stretched) Anus (a) Figure 26-12a

  19. Female Structures - Internal Organs • Vagina • Uterus • Cervix • Endometrium and myometrium • Fallopian tube • Fimbriae • Ovary

  20. Female Structures - Sagittal View ANATOMY SUMMARY THE FEMALE REPRODUCTIVE SYSTEM Ovary Fallopian tube Uterus Urinary bladder Cervix Rectum Urethra Vagina Clitoris (b) Labium minora Labium majora Anus Figure 26-12b

  21. Ovaries: Cells and Tissues • Follicle - structure where oocytes develop • Granulosa cells • Oocyte • Thecal cells surround all follicles • Corpus luteum

  22. Structure of the Uterus and Ovary Figure 26-12c–e

  23. Structure of the Uterine Wall Figure 26-12c, f

  24. Phases of the Ovarian Cycle • Follicular phase • Proliferation of granulosa cells • Development of antrum • Maturation of oocyte • Ovulation • Ripened follicle bursts, releasing oocyte • Luteal phase • Ruptured follicle develops into corpus luteum

  25. The Ovarian Cycle Figure 26-13 (1 of 2)

  26. Endometrial Lining: the Uterine Cycle • Menses (occurs if pregnancy is not achieved) • Bleeding from uterus as endometrium is shed • Proliferative phase • Endometrium grows in preparation for pregnancy • Secretoryphase • Endometrial secretions promote implantation

  27. The Uterine Cycle Figure 26-13 (2 of 2)

  28. Phases of theOvarian Cycle Follicular Phase Gonadotrophichormonelevels FSH LH Ovariancycle Primaryfollicle Theca Ovarianhormonelevels Estrogen Inhibin Progesterone Uterinecycle Phases of theUterine Cycle MENSES 36.7 Basal bodytemperature (–C) 36.4 DAYS 28/0 7 14 21 28/0 Follicular Phase and Menses Figure 26-13 (1 of 4)

  29. Phases of theOvarian Cycle Follicular Phase LH Gonadotrophichormonelevels FSH Ovariancycle Primaryfollicle Theca Antrum Ovarianhormonelevels Estrogen Inhibin Progesterone Uterinecycle PROLIFERATIVEPHASE Phases of theUterine Cycle MENSES 36.7 Basal bodytemperature (–C) 36.4 DAYS 28/0 7 14 21 28/0 Follicle Maturation and the Proliferative Phase Figure 26-13 (2 of 4)

  30. Ovulation, Luteal Phase, and Secretory Phase Phases of theOvarian Cycle Luteal Phase Ovulation Follicular Phase LH Gonadotrophichormonelevels FSH Ovariancycle Corpusluteumformation Primaryfollicle Ovulation Theca Antrum Ovarianhormonelevels Estrogen Inhibin Progesterone Uterinecycle PROLIFERATIVEPHASE Phases of theUterine Cycle MENSES SECRETORY PHASE 36.7 Basal bodytemperature (–C) 36.4 Figure 26-13 (3 of 4) DAYS 28/0 7 14 21 28/0

  31. Corpus Luteum Degenerates and Ceases Hormone Production Phases of theOvarian Cycle Luteal Phase Ovulation Follicular Phase LH Gonadotrophichormonelevels FSH Ovariancycle Corpusluteumformation Maturecorpusluteum Primaryfollicle Corpusalbicans Ovulation Theca Antrum Progesterone Ovarianhormonelevels Estrogen Inhibin Uterinecycle PROLIFERATIVEPHASE Phases of theUterine Cycle MENSES SECRETORY PHASE 36.7 Basal bodytemperature (–C) 36.4 Figure 26-13 (4 of 4) DAYS 28/0 7 14 21 28/0

  32. Complex Hormonal Control of Two Cycles • Ovarian and uterine cycles are controlled by several hormones, which display complex interactions • Extra-ovarian hormones • GnRH from the hypothalamus • FSH and LH from the anterior pituitary • Ovarian hormones • Estrogen • Progesterone

  33. Hormonal Control of the Menstrual Cycle LH FSH Ovum Follicle Corpus luteum Estrogen Inhibin Progesterone GnRH GnRH GnRH GnRH Hypothalamus Pituitary Tonic secretionresumes FSH LH FSH LH FSH LH FSH LH Corpus luteum(from ovulatedfollicle) Corpusluteumdies Follicle New folliclesbegin todevelop Follicle Thecalcells Granulosacells secretes Granulosacells Thecalcells Estrogen Androgens Inhibin Estrogen andprogesterone Progesterone Androgens Inhibin High estrogenoutput Small amount ofprogesterone Estrogens (a) Early to mid-follicular phase (b) Late follicular phase and ovulation (c) Early to mid-luteal phase (d) Late luteal phase Figure 26-14

  34. Hormonal Control of the Menstrual Cycle: Follicular Phase • FSH stimulates follicular development • Maturation to secondary and tertiary follicles • Granulosa cells produce estrogen • Negative feedback decreases FSH and LH secretion • Positive feedback allows continued estrogen production • LH stimulates thecal cells to produce androgens • Aromatase converts androgens into estrogens • Antrum fills with fluid

  35. Hormonal Control of the Menstrual Cycle: Follicular Phase LH FSH Ovum Follicle Corpus luteum Estrogen Inhibin Progesterone GnRH Hypothalamus Pituitary FSH LH Follicle Granulosacells Thecalcells Androgens Estrogens (a) Early to mid-follicular phase Figure 26-14 (1 of 4)

  36. Hormonal Control of the Menstrual Cycle: Late Follicular Phase and Ovulation • Late follicular phase • Secretion of inhibin and progesterone begins • Estrogen changes from negative to positive feedback • Enhanced secretion of LH - the LH surge • Meiosis resumes in developing follicles • Ovulation • Mature follicle secretes collagenase • Inflammatory reaction produces prostaglandins • Follicle ruptures releasing mature oocyte • Theca and granulosa cells change into luteal cells

  37. Hormonal Control of the Menstrual Cycle: Late Follicular Phase and Ovulation LH FSH Ovum Follicle Corpus luteum Estrogen Inhibin Progesterone GnRH GnRH Hypothalamus Pituitary FSH LH FSH LH Follicle Follicle Thecalcells Granulosacells Granulosacells Thecalcells Androgens Inhibin Androgens High estrogenoutput Small amount ofprogesterone Estrogens (a) Early to mid-follicular phase (b) Late follicular phase and ovulation Figure 26-14 (2 of 4)

  38. Hormonal Control of the Menstrual Cycle: Early to Mid-Luteal Phase • Corpus luteum develops and secretes progesterone and estrogen • Progesterone and estrogen exert negative feedback on hypothalamus • Effects of progesterone • Endometrium develops further • Cervical mucus thickens

  39. Hormonal Control of the Menstrual Cycle: Early to Mid-Luteal Phase LH FSH Ovum Follicle Corpus luteum Estrogen Inhibin Progesterone GnRH GnRH GnRH Hypothalamus Pituitary FSH LH FSH LH FSH LH Corpus luteum(from ovulatedfollicle) Follicle Follicle Thecalcells Granulosacells secretes Granulosacells Thecalcells Estrogen Androgens Inhibin Progesterone Androgens Inhibin High estrogenoutput Small amount ofprogesterone Estrogens (a) Early to mid-follicular phase (b) Late follicular phase and ovulation (c) Early to mid-luteal phase Figure 26-14 (3 of 4)

  40. Hormonal Control of the Menstrual Cycle: Late Luteal Phase • If no implantation • Corpus luteum undergoes apoptosis after 12 days • Lack of progesterone leads to death of endometrium • Menses = sloughing of the dead endometrium • FSH and LH secretion resumes • Following implantation • hcG maintains corpus luteum • Corpus luteum secretes progesterone and estrogen

  41. Hormonal Control of the Menstrual Cycle: Late Luteal Phase LH FSH Ovum Follicle Corpus luteum Estrogen Inhibin Progesterone GnRH GnRH GnRH GnRH Hypothalamus Pituitary Tonic secretionresumes FSH LH FSH LH FSH LH FSH LH Corpus luteum(from ovulatedfollicle) Corpusluteumdies Follicle New folliclesbegin todevelop Follicle Thecalcells Granulosacells secretes Granulosacells Thecalcells Estrogen Androgens Inhibin Estrogen andprogesterone Progesterone Androgens Inhibin High estrogenoutput Small amount ofprogesterone Estrogens (a) Early to mid-follicular phase (b) Late follicular phase and ovulation (c) Early to mid-luteal phase (d) Late luteal phase Figure 26-14 (4 of 4)

  42. Female Secondary Sex Characteristics • Secondary sexual characteristics are traits, other than genitalia, that distinguish males from females • Characteristics controlled by estrogen • Breast development • Distribution of body fat • Adrenal androgens control some female traits • Growth of pubic and axillary hair • Sex drive (libido)

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