Ch. 46 Warm-Up 1.What is the advantage of sex vs. asex(ual) reproduction? 2.List at least 3 different modes of asexual reproduction. 3.What are the 2 types of human gametes? Where is each produced? 4.Define and give an example of parthenogenesis.

Chapter 46 Animal Reproduction

What you must know: The hormonal control of the menstrual cycle How oogenesis and spermatogenesis differ

Types of Reproduction Asexual 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) Sexual Genetic diversity Advantage: ability to change pop. when env. changes Fusion of haploid gametes Egg (Ovum) + Sperm  Zygote

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

Reproductive Cycles and Patterns 1.Ovulation: release of mature eggs – Young produced when survival is most likely – Hormonal changes influenced by day length, season temp, rainfall or lunar cycles 2.Hermaphroditism: both M/F systems – Sessile/burrowing animals - barnacles, parasites (tapeworms), earthworms 3.Sex reversal: sex change during its lifetime – Bluehead wrasse (reef fish)

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 Egg shed by female, fert. by male in water Environmental cues / courtship behavior Large # gametes  low survival Eg. fish, amphibians Internal Fertilization 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

Evolution of sexual reproduction Least Complex No gonads Egg/sperm develop in undifferentiated cells Released into coelom, shed into env. Most Complex Distinct gonads (organs that produce gametes) Delivery systems

MALEFEMALE Function Produce & deliver sperm 1.produce eggs 2.development of baby Main reproductive organs Testes (singular: testis) Ovaries Reproductive cells (Gametes) Spermatogenesis  SPERMOogenesis  EGGS Main hormone TestosteroneEstrogens Role of FSH (follicle- stimulating hormone) Sperm formationEgg development (in follicle) Role of LH (luteinizing hormone) Produce testosteroneRelease of egg (ovulation) Human Reproductive System

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 million sperm/ejaculation

Male Reproductive System

Meiosis Spermatogenesis Sperm production Stem cells  spermatids in seminiferous tubules Mature & add tail in epidymis 4 motile sperm Oogenesis 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: 1.Follicular Phase : low estrogen,  FSH = egg develops in ovary 2.Ovulation (Day 14):  LH = egg released into Fallopian tube 3.Luteal Phase :  progesterone,  estrogen = lining of uterus thickens to prepare for pregnancy Egg travels down Fallopian tube, waits for fertilization 4.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

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

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

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