AP Biology Animal Reproduction Chapter 46.

AP Biology Sexual & asexual reproduction  Asexual  offspring all have same genes (clones)  no variation  Sexual  gametes (sperm & egg)  fertilization  mixing of genes  variation

AP Biology Parthenogenesis  Development of an unfertilized egg  honey bees  drones = males produced through parthenogenesis  haploid  workers & queens = females produced from fertilized eggs  diploid queenworkerdrone

AP Biology Different strokes… parthenogenesis in aphids “lesbian” lizards sex-change in fish gay penguins

AP Biology Hermaphrodites flat worm earthworms mating  Having functional reproductive system of both sexes

AP Biology Fertilization  Joining of egg & sperm  external  usually aquatic animals  internal  usually land animals

AP Biology Development  External  development in eggs  fish & amphibians in water  soft eggs= exchange across membrane  birds & reptiles on land  hard-shell amniotic eggs  structures for exchange of food, O 2 & waste  sharks & some snakes  live births from eggs  Internal  placenta  exchange food & waste  live birth

AP Biology Adaptive advantages?  What is the adaptive value of each type of sexual reproduction  number of eggs?  level of parental of care  habitat?

AP Biology Human Reproduction

AP Biology Reproductive hormones  Testosterone  from testes  functions  sperm production  2° sexual characteristics  Estrogen  from ovaries  functions  egg production  prepare uterus for fertilized egg  2° sexual characteristics LH & FSH testes or ovaries

AP Biology Sex hormone control in males Hypothalamus Pituitary Testes Body cells GnRH FSH & LH testosterone

AP Biology  Sperm production  over 100 million produced per day!  ~2.5 million released per drop! Male reproductive system

AP Biology Male reproductive system  Testicles  produces sperm & hormones  Scrotum  sac that holds testicles outside of body  Epididymis  where sperm mature  Vas deferens  tubes for sperm to travel from testes to penis  Prostate, seminal vesicles, Cowper’s (bulbourethal) glands  nutrient rich fluid to feed & protect sperm  buffer to counteract acids in vagina

AP Biology Male reproductive system  Testes & epididymis  sperm production & maturation  Glands  seminal vesicles, prostate, bulbourethal  produce seminal fluid = nutrient-rich seminiferous tubule sperm spermatocytes

AP Biology Spermatogenesis Epididymis Testis Coiled seminiferous tubules Vas deferens Cross-section of seminiferous tubule Spermatozoa Spermatids (haploid) 2° spermatocytes (haploid) 1° spermatocyte (diploid) Germ cell (diploid) MEIOSIS II MEIOSIS I

AP Biology Female reproductive system

AP Biology Female reproductive system  Ovaries  produces eggs & hormones  Uterus  nurtures fetus; lining builds up each month  Fallopian tubes  tubes for eggs to travel from ovaries to uterus  Cervix  opening to uterus, dilates 10cm (4 inches) for birthing baby  Vagina  birth canal for birthing baby

AP Biology Female reproductive system

AP Biology LH FSH estrogen progesterone lining of uterus egg developmentovulation = egg release corpus luteum days Menstrual cycle Hypothalamus Pituitary Ovaries Body cells GnRH FSH & LH estrogen

AP Biology Egg maturation in ovary  Corpus luteum  produces progesterone to maintain uterine lining

AP Biology Female hormones  FSH & LH  release from pituitary  stimulates egg development & hormone release  peak release = release of egg (ovulation)  Estrogen  released from ovary cells around developing egg  stimulates growth of lining of uterus  lowered levels = menstruation  Progesterone  released from “corpus luteum” in ovaries  cells that used to take care of developing egg  stimulates blood supply to lining of uterus  lowered levels = menstruation

AP Biology Oogenesis Meiosis 1 completed during egg maturation Meiosis 2 completed triggered by fertilization ovulation  What is the advantage of this development system?

AP Biology Fertilization

AP Biology Fertilization  Joining of sperm & egg  sperm head enters egg

AP Biology Cleavage  Repeated mitotic divisions of zygote  1st step to becoming multicellular  unequal divisions establishes body plan  different cells receive different portions of egg cytoplasm & therefore different regulatory signals

AP Biology Cleavage  zygote  morula  blastula  establishes future development

AP Biology Gastrulation  Establish 3 cell layers  ectoderm  outer layers  skin, nails, teeth, nerves  mesoderm  blood, bone & muscle  endoderm  inner lining  digestive system ectoderm mesoderm endoderm

AP Biology Neurulation  1st organ to form is notochord & nerve chord  develop into nervous system Neural groove Notochord Neural tube

AP Biology Organogenesis Umbilical blood vessels Chorion Amnion Yolk sac Allantois Fetal blood vessels Maternal blood vessels Bird embryo Mammalian embryo Placenta

AP Biology Placenta  Materials exchange across membranes

AP Biology Human Embryonic Development

AP Biology Sex determination XY XX Testes Y SpermZygote Ovum Sperm Ovum X X X Indifferent gonads SRY No SRY Ovaries (Follicles do not develop until third trimester) Seminiferous tubules Develop in early embryo Leydig cells

AP Biology Human fetal development  Day 1: 1 st cleavage  1 cell becomes 2 (2-cell stage)  Day 2: 2 nd cleavage  4-cell stage  Day 3: 6-12 cell stage  can test at this stage for genetic diseases if done by IVF  Day 4: cell stage  solid ball of cells = morula

AP Biology Ovulation to implantation

AP Biology Human fetal development  Day 5:  solid morula develops into hollow, fluid-filled blastula  embryo will develop from the inner cell mass, or embryonic disc  Day 6 -7:  blastocyst attaches to the endometrium (uterine lining) & burrows in: implantation  blastocyst starts to secrete HCG = human chorionic gonatotropin  stimulates estrogen & progesterone to prevent menstrual flow  causes "morning sickness" in some women...  pregnancy test measures the amount of this hormone!

AP Biology Human fetal developmental  Days :  pregnancy becomes established  fluid filled amniotic cavity starts to form  yolk sac starts to form  will make blood cells, germ cells  embryo starts to form from embryonic disc  chorion (placenta) starts to form  At the end of this stage, a woman will have just missed her period! Day 14

AP Biology Human fetal developmental  Days :  emergence of the vertebrate body plan  primitive streak starts to form  the site of gastrulation (formation of 3 tissue layers = ecto, endo, and mesoderm)  neural groove begins to form  future spinal cord & brain  somites begin to form  bands of tissue that will become muscles & bones  pharyngeal arches begin to form  future face, neck, mouth, nose

AP Biology Human embryonic developmental Day 24  Week 3 - Week 8 = embryo  development of all organ systems  Day 22: the heart begins to beat Day 28 Week 4

AP Biology Human embryonic development  embryo showing tail & limb buds

AP Biology Human embryonic development  beginning of the eye can be seen, as well the bulging heart & the umbilical cord

AP Biology Human embryonic development  lens of the eye can be seen forming, the mass of the heart bulging from the chest, & the beginnings of the finger rays

AP Biology Human fetal development 7 weeks4 weeks

AP Biology Human embryonic development

AP Biology Human embryonic development  beginning of the ear is clearly seen note the bend of the elbow joint has begun, the fingers are forming and toes are beginning to bud off the foot

AP Biology Human embryonic development  Note the formation of the nose, eyelids, ear flap & well defined toes & fingers 50–60 days (8 weeks) Both knee & elbow are visible. Embryo has formed most of basic organ systems & will spend remainder of development in “fetal” period. Organs grow, mature, & begin to learn their respective functions

AP Biology Human fetal development  Day 52:  first brain waves can be detected  weeks 4-8 is when all major organ systems of body are formed & when most teratogens have greatest effect Week 8

AP Biology Human fetal development 10 weeks

AP Biology Human fetal development  At 15 weeks the embryo begins to take on more of a typical baby's form & the attachment of umbilical cord can be clearly seen Week 15

AP Biology Human fetal development  Week 9 - week 40 = fetus  after 12 weeks or so, the baby's development is largely "finished"  some exceptions: brain & lung development Week 16

AP Biology Human fetal development  The fetus just spends much of the 2 nd & 3 rd trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid Week 20

AP Biology Human fetal development  24 weeks (6 months; 2nd trimester) fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix

AP Biology Human fetal development  30 weeks (7.5 months) umbilical cord

AP Biology Getting crowded in there!!  32 weeks (8 months) The fetus sleeps 90-95% of the day & sometimes experiences REM sleep, an indication of dreaming

AP Biology Birth Hormone induction positive feedback

AP Biology Intestine Placenta Umbilical cord Wall of uterus Vagina Cervix Birth (36 weeks) Bladder

AP Biology The end of the journey!