1. Chapter 46: Animal Reproduction Asexual reproduction Asexual reproduction Offspring from one parent; growth by mitosis Offspring from one parent; growth by mitosis Types Types Fission- equal division of cytoplasm (ex. Bacteria, paramecia) Fission- equal division of cytoplasm (ex. Bacteria, paramecia) Budding- unequal division of cytoplasm (ex. Cnidarians, yeast colonies, gemmule production in Porifera) Budding- unequal division of cytoplasm (ex. Cnidarians, yeast colonies, gemmule production in Porifera) Fragmentation- body broken into pieces Fragmentation- body broken into pieces Regeneration of lost parts Regeneration of lost parts Found in sponges, cnidarians, annelids, tunicates, & enchinoderms Found in sponges, cnidarians, annelids, tunicates, & enchinoderms Advantages Advantages Isolated individuals can reproduce without a mate Isolated individuals can reproduce without a mate Less time between generations Less time between generations Successful genotypes perpetuate Successful genotypes perpetuate

2. Sexual reproduction Sexual reproduction 2n offspring (zygote) produced by the fusion of egg & sperm 2n offspring (zygote) produced by the fusion of egg & sperm Gametes formed by meiosis Gametes formed by meiosis Female gamete=ovum Female gamete=ovum Male gamete=sperm Male gamete=sperm Offspring have characteristics of both parents resulting in species variation Offspring have characteristics of both parents resulting in species variation Reproductive cycles & patterns vary among animals Reproductive cycles & patterns vary among animals Often seasonally based & controlled by hormones Often seasonally based & controlled by hormones Parthenogenesis Parthenogenesis Development of an unfertilized egg into new individuals Development of an unfertilized egg into new individuals Ex. Aphids, bees, daphnia Ex. Aphids, bees, daphnia Hermaphrodites Hermaphrodites Individuals have functioning ovaries & testes Individuals have functioning ovaries & testes Self fertilization is rare Self fertilization is rare Found in slow moving, energy conserving organisms Found in slow moving, energy conserving organisms Sequential hermaphrodites Sequential hermaphrodites Individual reverses its sex Individual reverses its sex Ex. Some fish & oysters Ex. Some fish & oysters

3. Mechanisms of sexual reproduction External fertilization External fertilization Occurs in moist habitats to prevent desiccation & heat stress Occurs in moist habitats to prevent desiccation & heat stress Environmental cues & pheromones trigger release of gametes Environmental cues & pheromones trigger release of gametes Vertebrates (fish, amphibians) exhibit courtship behavior to ensure fertilization Vertebrates (fish, amphibians) exhibit courtship behavior to ensure fertilization Large numbers of zygotes result Large numbers of zygotes result few reach sexual maturity few reach sexual maturity Gelatinous coat covers the egg to permit gas & H 2 O exchange Gelatinous coat covers the egg to permit gas & H 2 O exchange

4. Internal fertilization Internal fertilization Fewer zygotes produced but more parental protection Fewer zygotes produced but more parental protection Requires Requires Cooperative behavior Cooperative behavior Copulatory organ for sperm delivery & a sperm receptacle for storage/transport Copulatory organ for sperm delivery & a sperm receptacle for storage/transport Mating behaviors to signal copulatory receptivity Mating behaviors to signal copulatory receptivity Adaptations include Adaptations include Shelled egg (“pond away from the pond”) in egg laying animals Shelled egg (“pond away from the pond”) in egg laying animals Reptiles & monotremes- amniotic egg with protein shell Reptiles & monotremes- amniotic egg with protein shell Birds- amniotic egg with calcium shell Birds- amniotic egg with calcium shell Mammals have internal embryonic development Mammals have internal embryonic development Marsupials- embryo in uterus for short time; completes development in maternal pouch Marsupials- embryo in uterus for short time; completes development in maternal pouch Eutherians (placental)- embryo in uterus until development complete Eutherians (placental)- embryo in uterus until development complete

5. Reproductive system complexity is not necessarily an indicator of phylogenetic relationship Reproductive system complexity is not necessarily an indicator of phylogenetic relationship Parasitic flatworms reproductive system is one of the most complex Parasitic flatworms reproductive system is one of the most complex Polycheates have separate sexes without distinct gonads Polycheates have separate sexes without distinct gonads Insects have separate sexes & complex reproductive tracts; females can store sperm for years after a single mating in the spermatheca Insects have separate sexes & complex reproductive tracts; females can store sperm for years after a single mating in the spermatheca Vertebrates have similar reproductive systems with some differences Vertebrates have similar reproductive systems with some differences Mammals have separate openings for digestion, excretion, & reproduction Mammals have separate openings for digestion, excretion, & reproduction Non-mammals have single opening=cloaca Non-mammals have single opening=cloaca Some mammals, birds, & snakes have a single branched uterus; most mammals have a divided uterus Some mammals, birds, & snakes have a single branched uterus; most mammals have a divided uterus Non-mammalian vertebrates do not have well developed penises & use other means to transfer spermatozoa Non-mammalian vertebrates do not have well developed penises & use other means to transfer spermatozoa

7. Mammalian Reproduction Human male Human male Testes develop & descend from the abdomen into the scrotum Testes develop & descend from the abdomen into the scrotum Sperm production requires a lower temperature Sperm production requires a lower temperature Penis is copulatory organ; ejaculatory duct joins urethra Penis is copulatory organ; ejaculatory duct joins urethra Human female Human female More complicated than the male More complicated than the male Produces female gamete Produces female gamete Houses embryo & developing fetus for gestation period Houses embryo & developing fetus for gestation period

13. Male reproductive tract Function Female reproductive tract function TestesSperm/testosteroneOvaries Ovum/estrogen & progesterone Seminiferous tubules SpermatogenesisOviduct Ciliated; location of fertilization Interstitial/Leydig cells Androgen production Uterus Thick, muscular, expandable Epididymus Sperm storage/maturation Endometrium Blood rich lining Vas deferens Muscular duct Cervix Neck of uterus Ejaculatory duct v. def. joins s. ves. Vagina Birth canal/ receive semen Urethra Drain semen Hymen Membrane covering vaginal opening Semen Mix of sperm & support fluids Vestibule Area surrounding vaginal opening Seminal vesicles Secretions to semen Labia minora & majora Folds & ridge of tissue Prostate gland Milky fluid; adjusts pH Clitoris Bulb of erectile tissue Bulbouethral gland Clear fluid; neutralizes the urethra Bartholin’s gland Lubrication of vagina/intercourse Prostaglandins Stimulate uterine contractions Mammary glands Lactating epithelial tissue Glans penis Foreskin Baculum Bone to stiffen penis in rodents, raccoons, whales

14. Human Sexual Response Cycle Coitus= sexual intercourse Coitus= sexual intercourse Excitement Excitement Vasocongestion of penis & clitoris (increased arterial blood flow) Vasocongestion of penis & clitoris (increased arterial blood flow) Myotonia- muscle tension Myotonia- muscle tension Plateau Plateau Stimulation of autonomic nervous system Stimulation of autonomic nervous system Orgasm Orgasm Rhythmic involuntary contractions of reproductive structures in both sexes Rhythmic involuntary contractions of reproductive structures in both sexes Resolution Resolution Reverses early responses Reverses early responses

15. Meiosis Spermatogenesis Spermatogenesis All 4 cell products become mature spermatozoa All 4 cell products become mature spermatozoa Continuous process; 100 million +sperm/day Continuous process; 100 million +sperm/day Oogenesis Oogenesis Unequal cytokinesis results in one ovum & 3 polar bodies Unequal cytokinesis results in one ovum & 3 polar bodies All potential ova present at birth as primary oocytes in the ovaries All potential ova present at birth as primary oocytes in the ovaries

19. Males Males Androgens (testosterone) produce primary & secondary sex characteristics Androgens (testosterone) produce primary & secondary sex characteristics GnRH from hypothalamus stimulates anterior pituitary to release LH & FSH GnRH from hypothalamus stimulates anterior pituitary to release LH & FSH LH- stimulates testosterone production LH- stimulates testosterone production FSH- stimulates sperm production in seminiferous tubules FSH- stimulates sperm production in seminiferous tubules Females Females Estrogen produces primary & secondary sex characteristics Estrogen produces primary & secondary sex characteristics Estrous cycle occurs in non-primate mammals Estrous cycle occurs in non-primate mammals “heat”; period of sexual activity surrounding ovulation “heat”; period of sexual activity surrounding ovulation Ovulation occurs after thickening of endometrium Ovulation occurs after thickening of endometrium Menstrual cycle in primates & humans Menstrual cycle in primates & humans Menstruation- shedding of endometrium Menstruation- shedding of endometrium Proliferative phase- regeneration of endometrium Proliferative phase- regeneration of endometrium Secretive phase- endometrium thickens & vascularizes Secretive phase- endometrium thickens & vascularizes Follicle phase- egg matures in follicle Follicle phase- egg matures in follicle Ovulation- egg is released Ovulation- egg is released Corpus luteum phase- follicle fills with yellow tissue mass; secretes progesterone Corpus luteum phase- follicle fills with yellow tissue mass; secretes progesterone Menopause- female stops menstruation & ovulation; ovaries no longer respond to LH & FSH Menopause- female stops menstruation & ovulation; ovaries no longer respond to LH & FSH Gestation period (conception to birth) Gestation period (conception to birth) Humans 266 days (38 weeks) Humans 266 days (38 weeks) Rodents 21 days Rodents 21 days Cows 270 days Cows 270 days Elephants 600 days Elephants 600 days Dogs 60 days Dogs 60 days

22. Development 1 st trimester 1 st trimester Conception in oviduct Conception in oviduct Cleavage- 24 hours after conception Cleavage- 24 hours after conception Implantation of blastocyst (sphere of cells) Implantation of blastocyst (sphere of cells) HcG secreted by corpus luteum to maintain progesterone HcG secreted by corpus luteum to maintain progesterone Placenta formation Placenta formation Organogenesis Organogenesis 8 weeks= fetus 8 weeks= fetus 2 nd trimester 2 nd trimester Fetus grows longer- up to 30 cm Fetus grows longer- up to 30 cm Movement detected Movement detected Placenta takes over progesterone production so HcG declines as corpus luteum disintegrates Placenta takes over progesterone production so HcG declines as corpus luteum disintegrates 3 rd trimester 3 rd trimester Fetus grows to 50 cm Fetus grows to 50 cm Mass increases rapidly Mass increases rapidly Maternal organs compressed Maternal organs compressed Labor Labor Induced by interplay of hormones estrogen, oxytocin, & prostaglandins Induced by interplay of hormones estrogen, oxytocin, & prostaglandins Parturition (birth) Parturition (birth) Dilation of cervix Dilation of cervix Strong uterine contractions through positive feedback Strong uterine contractions through positive feedback expulsion expulsion

27. Contraception Contraception Abstinence Abstinence Rhythm method Rhythm method Physical barriers… condoms, diaphragms, cervical caps, sponges Physical barriers… condoms, diaphragms, cervical caps, sponges Implants… IUD- spiral shaped device implanted into uterine entrance to prevent sperm entry Implants… IUD- spiral shaped device implanted into uterine entrance to prevent sperm entry Withdrawal Withdrawal Chemical contraception…prevents release of gametes (pill) Chemical contraception…prevents release of gametes (pill) Tubal ligation… closing oviducts Tubal ligation… closing oviducts Vasectomy… cutting of vas deferens Vasectomy… cutting of vas deferens Miscarriage…. Spontaneous abortion (1/3 of all pregnancies) Miscarriage…. Spontaneous abortion (1/3 of all pregnancies) Abortions… 1.5 million/year in US Abortions… 1.5 million/year in US RU-484… blocks progesterone receptors on uterus so pregnancy is not maintained RU-484… blocks progesterone receptors on uterus so pregnancy is not maintained

29. Modern technology Modern technology Ultrasound Ultrasound Non-invasive Non-invasive High frequency sound waves to “picture” fetus High frequency sound waves to “picture” fetus Sampling maternal blood Sampling maternal blood Used to detect fetal metabolic waste Used to detect fetal metabolic waste Amniocentesis Amniocentesis Invasive extraction of amniotic fluid to examine fetal cells Invasive extraction of amniotic fluid to examine fetal cells Chorionic villus sampling Chorionic villus sampling Invasive biopsy of placental tissue to detect genetic disorders Invasive biopsy of placental tissue to detect genetic disorders In vitro fertilization In vitro fertilization “test tube baby” “test tube baby” Mother egg & father sperm fuse in vitro (in glass) after several cleavages embryo is implanted into mother Mother egg & father sperm fuse in vitro (in glass) after several cleavages embryo is implanted into mother