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Sexual Reproduction

Sexual Reproduction. Female Reproductive System. Gonad: Ovaries. ovarian : each contains single immature egg (female cell ) granulosa cells: cells in that secrete estrogen (and progesterone ) NOTE: ~2 000 000 follicles at birth, but only ~400 000 follicles remain at puberty.

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Sexual Reproduction

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  1. Sexual Reproduction

  2. Female Reproductive System

  3. Gonad: Ovaries • ovarian : each contains single immature egg (female cell) • granulosa cells: cells in that secrete estrogen (and progesterone) • NOTE: ~2 000 000 follicles at birth, but only ~400 000 follicles remain at puberty

  4. Duct System • Oviduct (Fallopian tube): • tube that egg from ovary to uterus with cilia • site of • NOTE: when no fertilization occurs, then egg within 24–48h • Fimbria: finger–like projections at that sweep egg into oviduct withcilia

  5. Uterus (womb) • chamber where embryo (then fetus) • thick walls that consists of 2 : • myometrium: muscular outer lining that physically supports embryo and contracts during delivery • endometrium: inner lining that provides for developing embryo, which is shed during • menstruation takes place when no pregnancy occurs

  6. Duct System cervix: • connective tissue at lower end that uterus to hold embryo within uterus • expands labour vagina: • exterior that acts as birth canal and receives sperm from penis sexual intercourse • has low pH (acidic) to inhibit/kill

  7. ACCESORY ORGAN Clitoris: • external that resembles tiny penis, i.e. contains erectile tissue and nerve for sexual excitement • NOTE: required for sexual excitement, but not

  8. Female Hormones • FSH – Follicle Stimulating Hormone • Produced by the pituitary • Promotes the of a follicle in the ovary (which secretes estrogen and progesterone) • Too much in body inhibits FSH secretion, and the follicular phase comes to an end. • LH – Luteinizing Hormone • Produced by the Pituitary • Promotes the development of the corpus (secretes some progesterone and estrogen) • Too much progesterone in inhibits LH secretion, and as a result the corpus luteum begins to degenerate • Estrogen • Responsible for sex characteristics in females (hair and fat distribution) • Required for breast development • Progesterone • Involved in menstrual cycle • Pregnancy (embryo development) • for female sex characteristics

  9. Ovarian Cycle Follicular phase: Days 1 – 13 • increased FSH level development of follicle • developing follicle more estrogen, which inhibits secretion of FSH by negative feedback Ovulation: Day 14 • high level causes surge in LH by positive feedback, which causes follicle to rupture & secondary oocyte Luteal phase: Days 15 – 28 • LH surge initiates development of corpus luteum • developing corpus luteum more progesterone & some estrogen, which inhibits secretion of FSH & LH by negative feedback to prevent development of more follicles • if no pregnancy occurs, then low LH level causes corpus luteum to degenerate, which decreased estrogen & progesterone levels

  10. Uterine Cycle Proliferative phase: Days 6 – 13 • secretion of by developing follicle stimulates growth of endometrium, i.e. causes uterine to thicken Ovulation: Day 14 Secretory phase: Days 15 – 28 • secretion of progesterone (& some estrogen) by corpus luteum further growth of endometrium for implantation & of embryo, i.e. develops blood vessels and glands, and secretes mucous and glycogen • when corpus luteum , decreased estrogen & progesterone levels cause endometrium to begin degenerating Menstrual phase: Days 1 – 5 • blood & shed through vagina as endometrium continues to in random patches

  11. identify and give functions for each of the following: – ovaries (follicles and corpus luteum) – oviducts (fallopian tubes) – uterus – endometrium – cervix – vagina – clitoris • describe the functions of estrogen • describe the sequence of events in the ovarian cycle, with reference the follicular phase, ovulation, and the luteal phase • describe the sequence of events in the uterine cycle, with reference to menstruation, the proliferative phase, and the secretory phase • describe the control of the ovarian and uterine cycles by hormones including gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone • describe the hormonal changes that occur as a result of implantation, including – production of human chorionic gonadotropin (HCG) to maintain the corpus luteum – increased production of progesterone by the corpus luteum • describe a positive feedback mechanism involving oxytocin

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