Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst,...

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Exercise 44 Exercise 44 Survey of Survey of Embryonic Embryonic Development Development

Transcript of Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst,...

Page 1: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Exercise 44Exercise 44

Survey of Embryonic Survey of Embryonic DevelopmentDevelopment

Page 2: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Objectives:Objectives:

Fertilization, zygote, morula, Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta, amnion, chorionic villi, placenta, amnion, yolk sac, umbilical cordyolk sac, umbilical cord

Embryonic structures and Embryonic structures and functionsfunctions

Page 3: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

FertilizationFertilization Fusion of two haploid (1n) Fusion of two haploid (1n)

gametes, occurs in uterine gametes, occurs in uterine tube usually within a day after tube usually within a day after ovulationovulation SpermSperm

• Delivers paternal chromosomes Delivers paternal chromosomes to fertilization siteto fertilization site

Egg Egg • Provides all the cellular Provides all the cellular

organelles, nourishment, genetic organelles, nourishment, genetic programming for development programming for development AND maternal chromosomesAND maternal chromosomes

• ~2000x the volume of the sperm ~2000x the volume of the sperm cellcell

• Secondary oocyte has been Secondary oocyte has been suspended in Metaphase II until suspended in Metaphase II until nownow

Fig. 29-1Fig. 29-1

Page 4: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

ZygoteZygote

Product of fertilization (union of Product of fertilization (union of gametes)gametes)

Contains 46 chromosomes (normal # for Contains 46 chromosomes (normal # for a somatic cell)a somatic cell)

Fig. 29-1Fig. 29-1

Page 5: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Prenatal Development Prenatal Development **Atlas Diagrams**Atlas Diagrams

11stst trimester trimesterEmbryological & early fetal developmentEmbryological & early fetal developmentBeginnings of organ systems appearBeginnings of organ systems appear

22ndnd trimester trimesterOrgans and systems nearly completeOrgans and systems nearly complete

33rdrd trimester trimesterRapid fetal growthRapid fetal growthMost organ systems functionalMost organ systems functional

Page 6: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Embryonic Development: Embryonic Development: MORULAMORULA

Day 3-4 of development/cleavage (cell divisions)Day 3-4 of development/cleavage (cell divisions) Solid multicellular (> 4-cell stage) ballSolid multicellular (> 4-cell stage) ball Morula = “mulberry”Morula = “mulberry” Reaches uterus on day 4 Reaches uterus on day 4

Fig. 29-2Fig. 29-2

Page 7: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Embryonic Development: Embryonic Development: BLASTOCYSTBLASTOCYST

Fig. 29-2Fig. 29-2

Over next 2 daysOver next 2 days Hollow ball with inner cavityHollow ball with inner cavity Outer cellular layer (“trophoblast”, provides nutrients)Outer cellular layer (“trophoblast”, provides nutrients) Inner layer of cells (clustered at one end, Inner layer of cells (clustered at one end, will form the will form the

embryoembryo)) Implants in uterine wallImplants in uterine wall

Page 8: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Embryonic Development: Embryonic Development: GASTRULAGASTRULA

Day 12Day 12 Third layer forms—cells on surface migrate to central line: “primitive Third layer forms—cells on surface migrate to central line: “primitive

streak”streak” Migrating cells move between the 2 layers Migrating cells move between the 2 layers Now have 3 embryonic layers:Now have 3 embryonic layers:

EctodermEctodermMesoderm Mesoderm Endoderm Endoderm

Fig. 29-4Fig. 29-4

Page 9: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Embryonic Germ LayersEmbryonic Germ Layers

EctodermEctoderm

MesodermMesoderm

Endoderm Endoderm Fig. 29-4Fig. 29-4

Neural tissueNeural tissue

Epithelia Epithelia &&

glandsglands

Connective tissuesConnective tissues

Muscle tissueMuscle tissue

Page 10: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Embryo to FetusEmbryo to Fetus

Fetus: Fetus: Start of month 3 to Start of month 3 to

deliverydelivery

Fig. 29-5Fig. 29-5

Page 11: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Extra-embryonic membranesExtra-embryonic membranes

Yolk sacYolk sacEndoderm & mesodermEndoderm & mesoderm

AmnionAmnionEctoderm & mesodermEctoderm & mesoderm

AllantoisAllantois Endoderm & mesodermEndoderm & mesoderm

ChorionChorionMesoderm & trophoblastMesoderm & trophoblast

Page 12: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Yolk sacYolk sac

Fig. 29-5Fig. 29-5

Endoderm + mesodermEndoderm + mesoderm PouchPouch Important site of blood Important site of blood

cell formationcell formation

Page 13: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Fig. 29-5Fig. 29-5

Ectoderm + mesodermal cells Ectoderm + mesodermal cells form this two layered structureform this two layered structure

Enlarges throughout Enlarges throughout developmentdevelopment

Amniotic cavity contains Amniotic cavity contains amniotic fluidamniotic fluid Surrounds, cushions Surrounds, cushions

developing embryo/fetusdeveloping embryo/fetus

AmnionAmnion

Page 14: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

ChorionChorion Mesoderm and trophoblast cells form this vascular Mesoderm and trophoblast cells form this vascular

layerlayer Provides transport of nutrients to the growing Provides transport of nutrients to the growing

embryo/fetus (multicellular now, so diffusion alone embryo/fetus (multicellular now, so diffusion alone won’t suffice)won’t suffice)

Chorionic villiChorionic villi: branches in contact with maternal : branches in contact with maternal tissuestissues Embryonic blood vessels in each Embryonic blood vessels in each Supplies embryonic heart (beating by week 3)Supplies embryonic heart (beating by week 3) Gases and nutrients diffuse between embryonic Gases and nutrients diffuse between embryonic

and maternal circulations—no mixing of actual and maternal circulations—no mixing of actual blood (separated by trophoblast)blood (separated by trophoblast)

Page 15: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Fig. 29-6Fig. 29-6

ChorionChorion

Page 16: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

PlacentaPlacenta Appearance of blood vessels in Appearance of blood vessels in

the chorion = 1the chorion = 1stst step in creation step in creation of a functional placentaof a functional placenta

Temporary structure in uterine Temporary structure in uterine wall that allows the diffusion wall that allows the diffusion between fetal and maternal between fetal and maternal circulatory systemscirculatory systems

Fetal sideFetal side Maternal sideMaternal side

Fig. 29-6Fig. 29-6

Page 17: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Umbilical cordUmbilical cord Connection between fetus and Connection between fetus and

placentaplacenta Contains the allantois, placental Contains the allantois, placental

blood vessels, & yolk stalk of blood vessels, & yolk stalk of the yolk sacthe yolk sac

Fig. 29-6Fig. 29-6

Page 18: Exercise 44 Survey of Embryonic Development. Objectives: Fertilization, zygote, morula, blastocyst, gastrula, fetus, chorion, chorionic villi, placenta,

Fig. 29-8Fig. 29-8

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Fig. 29-10Fig. 29-10

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Video:Video:

The Miracle of LifeThe Miracle of Life