Ch. 46 Warm-Up What is the advantage of sex vs. asex(ual) reproduction? List at least 3 different modes of asexual reproduction. What are the 2 types of human gametes? Where is each produced? Define and give an example of parthenogenesis.

Chapter 46 Animal Reproduction

Egg (Ovum) + Sperm  Zygote Types of Reproduction Asexual Sexual Clone Advantage: FAST, if env. is stable Fission: parent separates into 2+ individuals of same size Budding: outgrowths from parent (eg. cnidarians, tunicates) Fragmentation: breaking of body into pieces, form into adults by regeneration (eg. sea stars, sponges, cnidarians) Parthenogenesis: female produces eggs that develop w/o fertilization (eg. male bees – haploid) Genetic diversity Advantage: ability to change pop. when env. changes Fusion of haploid gametes Egg (Ovum) + Sperm  Zygote

Sexual Reproduction – Frogs (External fertilization) Fission - Sea Anemone Sexual Reproduction – Frogs (External fertilization)

Reproductive Cycles and Patterns Ovulation: release of mature eggs Young produced when survival is most likely Hormonal changes influenced by day length, season temp, rainfall or lunar cycles Hermaphroditism: both M/F systems Sessile/burrowing animals - barnacles, parasites (tapeworms), earthworms Sex reversal: sex change during its lifetime Bluehead wrasse (reef fish)

Sex reversal in a sequential hermaphrodite Sex reversal in a sequential hermaphrodite. Wrasses (reef fish) born female, but oldest, largest individuals complete their lives as males. Parthenogenesis in female Blacktip Shark: egg fuses with a polar body

Fertilization = sperm + egg External Fertilization Internal Fertilization Egg shed by female, fert. by male in water Environmental cues / courtship behavior Large # gametes  low survival Eg. fish, amphibians Sperm deposited in female reprod. tract Cooperative behavior Dry environment Fewer gametes, fewer zygotes  greater survival External Devel. Tough eggshell Eg. reptiles, birds, platypus Internal Devel. High parental care Eg. placentals, sharks, some reptiles

Human Reproductive System MALE FEMALE Function Produce & deliver sperm produce eggs development of baby Main reproductive organs Testes (singular: testis) Ovaries Reproductive cells (Gametes) Spermatogenesis  SPERM Oogenesis  EGGS Main hormone Testosterone Estrogens Role of FSH (follicle-stimulating hormone) Sperm formation Egg development (in follicle) Role of LH (luteinizing hormone) Produce testosterone Release of egg (ovulation)

Female Anatomy Ovaries – produce eggs, sex hormones Follicles – contain oocyte (egg); release 1/month; produce estrogens Ovulation – release of egg from follicle Remaining follicle  corpus luteum (↑hormones) egg  oviduct (fallopian tube)  uterus (baby)  cervix  vagina Mammary glands – secrete milk through nipples in breast

Female Reproductive System

Male Anatomy Testes (inside scrotum) – produce sperm, sex hormones Seminiferous tubules – make sperm seminiferous tubules  epididymis  vas deferens  urethra (penis) semen = alkaline fluid w/nutrients, enzymes 100-650 million sperm/ejaculation

Male Reproductive System

Meiosis Spermatogenesis Oogenesis Sperm production Stem cells  spermatids in seminiferous tubules Mature & add tail in epidymis 4 motile sperm Ova production Before birth: oogonia  meiosis - STOP at Prophase I (primary oocytes) Puberty: each month, egg in follicle  Meiosis I (secondary oocytes)  fertilization  Meiosis II 1 ovum + 3 polar bodies

Menstrual cycle – humans & other primates Prepare and release egg for fertilization Prepare uterus to receive a fertilized egg Estrous cycle – other mammals; no menstruation

Four Phases of Menstrual Cycle: Follicular Phase : low estrogen, FSH = egg develops in ovary Ovulation (Day 14): LH = egg released into Fallopian tube Luteal Phase : progesterone, estrogen = lining of uterus thickens to prepare for pregnancy Egg travels down Fallopian tube, waits for fertilization Menstruation (no fertilization) : P/E = lining of uterus breaks down Blood and unfertilized egg discharged

Human female reproductive cycle

Human embryonic development Conception: in oviduct Implantation: in uterus Hormones: Human Chorionic Gonadotropin (hCG): maintain estrogens in early pregnancy; pregnancy test Human gestation (pregnancy) = 40 weeks Rodents (21 days); Dogs (60 days); Cows (270 days); Elephants (600 days) Egg lodged in oviduct = ectopic (tubal) pregnancy

Formation of Zygote Cleavage starts Cleavage continues Ovary Fertilization occurs The blastocyst implants Uterus Ovulation Endometrium From ovulation to implantation

Early Postfertilization Events Endo- metrium Inner cell mass Cavity Trophoblast Blastocyst Implantation of blastocyst

Placental Circulation

Human Fetal Development

The Three Stages of Labor

How does “the Pill” work? “the Pill” is an oral contraceptive Contains estrogen and progesterone First available in 1960 Main effect: Prevent ovulation Other effects: Thickens cervical mucus – slows down sperm Thins uterus lining – prevent implantation of fertilized egg Usage: active pill for 21 days, inactive pills for 7 days (“period”) Other medical uses: Medication for mild/moderate acne Decrease painful menstruation Treat polycystic ovary syndrome (PCOS) Correct irregular menstrual cycle Reduce risk of ovarian and endometrial cancers

Mechanisms of some contraceptive methods