Exploring Reproduction: From Gametes to Birth

2. Chapter 46 Reading Quiz • In ____ reproduction, two haploid ____ fuse to form a ____. • Which tubes within the male produce sperm? • Which female hormone induces uterine contractions?

3. 1. Distinguish between sexual and asexual reproduction, including relevant terms. • Sexual  the fusion of gametes (n) to form a zygote (2n) - gametes are formed by meiosis - ovum (unfertilized egg) - spermatozoon (male gamete) • Asexual  new individuals whose genes are from one parent - relies on mitosis 

5. 2. Define budding, fission, fragmentation, and regeneration. Why are these considered reproduction? • Fission  separation of a parent into 2 individuals of equal size (sea anemone) • Budding  new individuals splitting off from an existing individual (sponges) • Fragmentation  the breaking of an individual into several pieces (sponges) • Regeneration  the regrowth of lost body parts (some sea stars) 

6. 3. Describe how reproductive cycles and patterns vary extensively among animals. • Cycles are controlled by hormonal & environmental cues • May alternate between sexual & asexual • Parthenogenesis  development of egg without fertilization • Hermaphroditism  produce both male and female gametes - sequential hermaphroditism  reverses sex (some fish, oysters) 

8. 4. Distinguish between internal and external fertilization and define pheromones. • Internal  fertilization occurs inside the female’s body - requires more cooperative mating behaviors • External  fertilization occurs in the environment - occurs almost exclusively in moist environments - environmental cues and pheromones trigger release of gametes • Pheromones  chemical signals between organisms of the same species - easily dispersed in environment 

10. 5. Describe mammalian reproduction. a. briefly overview the male & female anatomy • Male  • external: scrotum & penis • internal: testes, glands, & ducts - seminiferous tubules  sperm form - interstitial cells  produce testosterone - epididymis  tubules, store sperm - vas deferens  duct at ejaculation - seminal vesicles  secrete fluid (energy for sperm & prostaglandins for uterine contraction) - prostate  produces fluid, balances acidity of vagina - bulbourethral glands  fluid for acidity 

12. Female  • Ovaries, ducts, and chambers • External  clitoris & labia • Ovaries with eggs, all formed at birth, develop in follicles, which produce estrogens • Every menstrual cycle one follicle matures and releases the egg • Ovulation  egg is expelled from follicle, remaining tissue forms the corpus luteum, which secretes progesterone (which maintains uterine lining) and more estrogen - if egg is not fertilized, corpus luteum degenerates - egg is expelled and drawn into uterus with cilia • Uterus  thick muscular organ to accommodate a fetus 

15. Continued… • Endometrium  the inner uterine lining, richly supplied with blood vessels • Cervix  neck of uterus, opens into vagina • Vagina  thin-walled chamber, birth canal • Hymen  membrane that covers vaginal opening and is broken during activity • Bartolin’s glands  glands that lubricate the vagina • Mammary glands (not part of reproductive system, but important in reproduction)  small sacs of epithelial tissue that secrete milk 

16. b. describe how spermatogenesis & oogenesis differ (page 984) • Spermatogenesis  the production of mature sperm cells - continuous & prolific - each ejaculation contains 100-650 million • Oogenesis  the development of ova; between birth & puberty, the egg cells enlarge and follicles grow - ovum & polar bodies result after meiosis 

19. c. describe the male & female interplay of hormones • Males  androgens, primary & secondary sex characteristics, also sex drive and aggressiveness - controlled by the hypothalamus and anterior pituitary • Females  estrous cycle: non-primate animals, endometrium reabsorbed - menstrual: average 28 days 1. Menstrual flow 2. Proliferative: regeneration & thickening 3. Secretory: continued endometrium development • Hormones next slide 

22. 6. Describe the development between conception and birth. • Conception  sperm meets in oviduct, cleavage begins in 24 hours, becomes blastocyst and reached uterus in 3-4 days • Implantation  egg meets uterine lining within the week, 2-4 weeks begins to obtain nutrients • Placenta  functions in gas exchange, nutrient transfer, and waste removal 

25. Continued.. • First trimester  organogenesis - after 8 weeks all organs are present - fetus 5cm long - embryo secretes hormones to signal presence - human chorionic gonadotropin (hCG) maintains progesterone & estrogen levels to prevent menstruation • Second trimester  rapid growth, 30 cm - placenta secretes progesterone, pregnancy obvious • Third trimester  rapid growth, 50 cm - maternal organs become compressed & displaced - labor is induced: estrogen, oxytocin, progesterone - Parturition  birth and then placenta is expelled 4. Lactation  decreased levels of progesterone, increased prolactin (after 2-3 days), then oxytocin 

26. 5 weeks 14 weeks 20 weeks

29. 7. Briefly overview reproductive immunology. • Embryo does have foreign markers; why the mother doesn’t reject this foreign body is not completely understood • The trophoblast is a protective layer between mom & baby that prevents tissue contact • White blood cell suppression • Miscarriage issues 

30. 8. Describe the various contraception options. • Keep eggs and sperm apart - rhythm method (10-20% failure) - condoms, diaphragms, cervical caps, sponges, spermicidal (fails <10%) 2. Prevent implantation of embryo - intrauterine device (IUD) • Prevent release of mature eggs & sperm a. chemical contraception (fails <1%) - blocks LH release, progestin prevents ovulation - estrogen inhibits FSH so no follicles develop b. sterilization  snip snip! 100% effective 

32. 9. Describe how modern technology offers solutions for some reproductive problems. • Ultrasound • Maternal blood sampling • Amniocentesis  fluid withdrawn • Chorionic villus sampling  bit of placenta analyzed for problems • In vitro fertilization 