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Animal Reproduction

Animal Reproduction. Modes of Reproduction. 2 modes: asexual reproduction fission budding regeneration parthenogenesis. Modes of Reproduction. sexual reproduction fertilization internal and external hermaphroditism sequential hermaphroditism. Reproductive Systems.

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Animal Reproduction

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  1. Animal Reproduction

  2. Modes of Reproduction • 2 modes: • asexual reproduction • fission • budding • regeneration • parthenogenesis

  3. Modes of Reproduction • sexual reproduction • fertilization • internal and external • hermaphroditism • sequential hermaphroditism

  4. Reproductive Systems • simplest animals do not have gonads (produce gametes) • polychaetes’ gametes develop from undifferentiated cells lining the coelom • more complex animals have gonads and a system of ducts and glands

  5. Reproductive Systems • non-mammalian vertebrates possess a cloaca • mammals have separate openings for each system

  6. Spermatogenesis • sperm structure: • head • acrosome • midpiece • tail

  7. Oogenesis • production of an ovum • occurs in the ovaries

  8. Regulation of Male Reproductive System

  9. Regulation of Female Reproductive System • pattern of hormone secretion is cyclic • menstrual cycle • endometrium is shed if no implantation occurs (menstruation) • estrous cycle • endometrium is reabsorbed

  10. Menstrual Cycle • average length is 28 days • refers to changes in uterus • 1. Menstrual flow phase • menstrual bleeding • 2. Proliferative phase • endometrium regenerates • Secretory phase (about 2 weeks long) • glands in endometrium secrete glycogen

  11. Ovarian Cycle • 1. Follicular phase • several follicles begin to grow • ends in ovulation • 2. Luteal phase • follicle cells remaining after ovulation develop into corpus luteum

  12. Hormonal Control • Follicular phase • FSH and LH secreted in response to GnRH • follicle cells have only FSH receptors • follicle cells secrete estrogens • slow rise in estrogen levels, keeping FSH and LH levels steady

  13. Hormonal Control • positive feedback- sharp increase in estrogens cause sharp increase in FSH and LH (increases GnRH release) • LH receptors develop on follicle cells • high LH causes final follicle maturation • ovulation occurs about 1 day after LH surge

  14. Hormonal Control • Luteal phase • LH stimulates follicle cells to form corpus luteum • corpus luteum releases progesterone and estrogens • negative feedback- production of progesterone and estrogen inhibits release of LH and FSH

  15. Hormonal Control • corpus luteum disintegrates in 8-10 days, releasing negative feedback • FSH production resumes and the cycle continues over again • ovarian cycle and menstrual cycle are sychronized

  16. Hormonal Control • follicular phase and proliferative phase are linked • estrogens cause endometrium to thicken • uterus is prepared for implantation before ovulation • luteal phase and secretory phase are linked • estrogens and progesterone maintain endometrial lining

  17. Hormonal Control • rapid drop in ovarian hormones after corpus luteum disintegrates causes arteries in endometrium to spasm, depriving endometrium of blood • menstruation results

  18. Menopause • cessation of ovulation and menstruation • ovaries lose responsiveness to FSH and LH

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