Transcript 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) Male Reproductive Structures - Erectile Tissues Figure 26-8 (2 of 2) 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) Male Reproductive Structures - Sagittal View ANATOMY SUMMARY THE MALE REPRODUCTIVE SYSTEM Ureter Urinary bladder Seminal vesicle Rectum Prostate gland Bulbourethral gland Pubic symphysis Vas deferens Ejaculatory duct Urethra Penis Epididymis Testis Scrotum (a) Figure 26-9a 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 Seminiferous Tubule - Cross-Section ANATOMY SUMMARY THE MALE REPRODUCTIVE SYSTEM Capillary Sertoli cell Leydig cell Spermatogonium (c) Figure 26-9c 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 Seminiferous Tubule - Detail ANATOMY SUMMARY THE MALE REPRODUCTIVE SYSTEM Lumen of seminiferous tubule Spermatids Secondary spermatocyte Primary spermatocyte Spermatogonium Tight junction between Sertoli cells Fibroblast (d) Spermatozoa Sertoli cells Basal lamina Capillary Leydig cells Figure 26-9d Spermatozoa Structure Head Acrosome contains enzymes Mid piece Nucleus Centrioles Mitochondrial spiral Tail (flagellum) Microtubules Figure 26-10 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 Regulation of Spermatogenesis GnRH Hypothalamus Anterior pituitary FSH LH Leydig cells Spermatogonium Inhibin Testes Sertoli cell Testosterone (T) Spermatocyte Second messenger Sertoli cell To body for secondary effects Cell products Androgen-binding protein (ABP) ABP T Figure 26-11 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 • Bulbourethral gland – mucus, buffers Accessory Glands Contribute to Semen Table 26-3 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 Female Reproductive Structures • External genitalia (aka vulva, or pudendum) • • • • Labia majora Labia minora Clitoris Vagina • Hymen • Urethral opening is inside the labia minora Female Structures - External Genitalia ANATOMY SUMMARY THE FEMALE REPRODUCTIVE SYSTEM Clitoris Labium minora Urethral opening Labium majora Vagina Hymen (stretched) Anus (a) Figure 26-12a Female Structures - Internal Organs • Vagina • Uterus • Cervix • Endometrium and myometrium • Fallopian tube • Fimbriae • Ovary Female Structures - Sagittal View ANATOMY SUMMARY THE FEMALE REPRODUCTIVE SYSTEM Ovary Fallopian tube Uterus Urinary bladder Cervix Rectum Urethra Vagina Clitoris (b) Labium Labium minora majora Anus Figure 26-12b Ovaries: Cells and Tissues • Follicle - structure where oocytes develop • Granulosa cells • Oocyte • Thecal cells surround all follicles • Corpus luteum Structure of the Uterus and Ovary Figure 26-12c–e Structure of the Uterine Wall Figure 26-12c, f 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 The Ovarian Cycle Figure 26-13 (1 of 2) 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 • Secretory phase • Endometrial secretions promote implantation The Uterine Cycle Figure 26-13 (2 of 2) Follicular Phase and Menses Phases of the Ovarian Cycle Follicular Phase Gonadotrophic hormone levels FSH LH Ovarian cycle Primary follicle Ovarian hormone levels Theca Estrogen Inhibin Progesterone Uterine cycle Phases of the Uterine Cycle MENSES 36.7 Basal body temperature (–C) 36.4 DAYS 28/0 7 14 21 28/0 Figure 26-13 (1 of 4) Follicle Maturation and the Proliferative Phase Phases of the Ovarian Cycle Follicular Phase LH Gonadotrophic hormone levels FSH Ovarian cycle Primary follicle Ovarian hormone levels Theca Antrum Estrogen Inhibin Progesterone Uterine cycle Phases of the Uterine Cycle MENSES PROLIFERATIVE PHASE 36.7 Basal body temperature (–C) 36.4 DAYS 28/0 7 14 21 28/0 Figure 26-13 (2 of 4) Ovulation, Luteal Phase, and Secretory Phase Phases of the Ovarian Cycle Follicular Phase Ovulation Luteal Phase LH Gonadotrophic hormone levels FSH Ovarian cycle Primary follicle Ovarian hormone levels Corpus Theca Antrum Ovulation luteum formation Estrogen Inhibin Progesterone Uterine cycle Phases of the Uterine Cycle MENSES PROLIFERATIVE PHASE SECRETORY PHASE 36.7 Basal body temperature (–C) 36.4 DAYS 28/0 7 14 21 28/0 Figure 26-13 (3 of 4) Corpus Luteum Degenerates and Ceases Hormone Production Phases of the Ovarian Cycle Follicular Phase Ovulation Luteal Phase LH Gonadotrophic hormone levels FSH Ovarian cycle Primary follicle Ovarian hormone levels Corpus Mature Corpus Theca Antrum Ovulation luteum corpus albicans formation luteum Progesterone Estrogen Inhibin Uterine cycle Phases of the Uterine Cycle MENSES PROLIFERATIVE PHASE SECRETORY PHASE 36.7 Basal body temperature (–C) 36.4 DAYS 28/0 7 14 21 28/0 Figure 26-13 (4 of 4) 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 Hormonal Control of the Menstrual Cycle LH FSH Ovum Follicle Corpus luteum Estrogen Inhibin Progesterone GnRH GnRH GnRH GnRH Hypothalamus Pituitary Tonic secretion resumes FSH FSH LH LH Follicle Follicle Granulosa cells Granulosa cells Thecal cells Androgens Estrogens (a) Early to mid-follicular phase Inhibin High estrogen output FSH LH Corpus luteum (from ovulated follicle) Thecal cells secretes Androgens Estrogen Progesterone Inhibin FSH New follicles begin to develop LH Corpus luteum dies Estrogen and progesterone Small amount of progesterone (b) Late follicular phase and ovulation (c) Early to mid-luteal phase (d) Late luteal phase Figure 26-14 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 Hormonal Control of the Menstrual Cycle: Follicular Phase LH FSH Ovum Follicle Corpus luteum Estrogen Inhibin Progesterone GnRH Hypothalamus Pituitary FSH LH Follicle Granulosa cells Thecal cells Androgens Estrogens (a) Early to mid-follicular phase Figure 26-14 (1 of 4) 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 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 FSH LH LH Follicle Follicle Granulosa cells Thecal cells Androgens Estrogens (a) Early to mid-follicular phase Granulosa cells Inhibin Thecal cells Androgens High estrogen Small amount of output progesterone (b) Late follicular phase and ovulation Figure 26-14 (2 of 4) 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 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 FSH LH LH Follicle Follicle Granulosa cells Thecal cells Androgens Estrogens (a) Early to mid-follicular phase Granulosa cells Inhibin FSH LH Corpus luteum (from ovulated follicle) Thecal cells secretes Androgens Estrogen Progesterone Inhibin High estrogen Small amount of output progesterone (b) Late follicular phase and ovulation (c) Early to mid-luteal phase Figure 26-14 (3 of 4) 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 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 secretion resumes FSH FSH LH LH Follicle Follicle Granulosa cells Thecal cells Androgens Estrogens (a) Early to mid-follicular phase Granulosa cells Inhibin FSH LH Corpus luteum (from ovulated follicle) Thecal cells secretes Androgens Estrogen Progesterone Inhibin FSH New follicles begin to develop LH Corpus luteum dies Estrogen and progesterone High estrogen Small amount of output progesterone (b) Late follicular phase and ovulation (c) Early to mid-luteal phase (d) Late luteal phase Figure 26-14 (4 of 4) 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)