1 / 16

Animal Reproduction

Animal Reproduction. Overview Mechanisms of Sexual Reproduction Mammalian Reproduction. Overview. Asexual vs Sexual, when? Fission, fragmentation, budding Parthenogenesis-development of the egg without fertilization Hermaphroditism, most do not self fertilize, what evolutionary value?

mattox
Download Presentation

Animal Reproduction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Animal Reproduction Overview Mechanisms of Sexual Reproduction Mammalian Reproduction

  2. Overview • Asexual vs Sexual, when? • Fission, fragmentation, budding • Parthenogenesis-development of the egg without fertilization • Hermaphroditism, most do not self fertilize, what evolutionary value? • Sequential hermaproditism-sex change, associated with age and size

  3. External fertilization almost exclusive in moist habitats environmental cue and pheromones trigger simultaneous release of gametes vertebrates exhibit courtship behaviors, value? Internal fertilization requires sophisticated reproductive systems and behaviors produce fewer zygotes, but more parental protection Internal vs. External Fertilization

  4. Male: penis, scrotum, testes testes comprised of seminiferous tubules, interstitial cells, and epididymis accessory glands: seminal vesicle, prostate gland, bulbourethral gland Female: ovaries, fallopian tubes, uterus, cervix, vagina, vestibule, labia majora, labia minora, clitoris, Bartholin’s glands Mammary glands Mammalian Reproduction

  5. Spermatogenesis: occurs in seminiferous tubules mature sperm is a haploid nucleus with a tail, an acrosome and a mitochondiral spiral continuous process 4 cells per meiotic event Oogenesis: one cell per meiotic event polar bodies characterized by equal karyokinesis and unequal cytokinesis “resting” periods between initial and final product Spermatogenesis vs Oogenesis

  6. The Male Pattern • Androgens directly responsible for primary and secondary sexual characteristics • Type of steroid hormone • Testosterone most important • Aggressive behavior • GnRH, LH and FSH all have roles in the male pattern

  7. Female Pattern • More complicated, two types of cycles exist: • Estrus cycles-non-primates, endometrium is reabsorbed if no fertilization (no period), seasonal and climatic changes effect this cycle, only period of sexual activity • Menstrual cycle-humans and primates, if no fertilization, endometrium is shed, fertile on 20-40 day cycle

  8. Menstrual Cycle: Three Phases • Menstrual flow phase: endometrium is discharged, persists only a few days, first day of this phase is day one of the cycle • Proliferative phase: regeneration and thickening of the endomentrium (one to two weeks) • Secretory phase: endometrium continues to develop (2 weeks)

  9. Ovarian Cycle Parallels menstrual (uterine) cycle, two phases: • Follicular phase: egg(s) mature within follicle(s) • Luteal phase: follows ovulation, follicle tissue forms corpus luteum

  10. Hormones Coordinate Menstrual and Ovarian Cycles • GnRH- released from hypothalamus, targets anterior pituitary • FSH and LH released from anterior pituitary and target ovary • Estrogen and Progesterone released from the ovary and target the uterine lining and the hypothalamus • Menopause-menstrual and ovarian cycles stop

  11. Development • Pregnancy (gestation): internal development of the embryo(s) • divided into 3 trimesters • 1st trimester: fertilization, cleavage, blastocyst, implantation, organogenesis all occur • 2nd trimester: rapid growth, embryo now a fetus, very active • 3rd trimester: activity decreases, rapid growth

  12. Websites and Videos • http://www.youtube.com/watch?v=8sgyxMb9awE&feature=related

More Related