Perkemb_ Hwn & Mns-olympic_sofy08-Edit

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Pembinaan Kompetensi siswa SMP/MTs Pembinaan Kompetensi siswa SMP/MTs

untuk Olimpiade Sains Nasional 2008 untuk Olimpiade Sains Nasional 2008

by Sofy PERMANA

PERKEMBANGAN HEWAN DAN

CIRI-CIRI MANUSIA BERDASARKAN USIA



PERKEMBANGAN HEWAN DAN CIRI-CIRI

MANUSIA BERDASARKAN USIA

Drs. H. A. Sofy PERMANA, MSc.,DSc.Drs. H. A. Sofy PERMANA, MSc.,DSc.

Department of Biology Department of Biology

Faculty of Mathematics and Natural Sciences Faculty of Mathematics and Natural Sciences

Brawijaya University Brawijaya University

Malang Malang



Introduction :Introduction :

What is Development ?What is Development ? Includes all stages in the life of an individualIncludes all stages in the life of an individual

focus on thefocus on the early stagesearly stages ±± fertilization to birthfertilization to birth

What happens during this time?What happens during this time?

Fusion of egg and sperm forms the zygoteFusion of egg and sperm forms the zygote

The zygote undergoes division to increase numbers of cellsThe zygote undergoes division to increase numbers of cells

It becomes more complexIt becomes more complex

It grows in sizeIt grows in size

The cells undergo changes in gene expression and soThe cells undergo changes in gene expression and so

change with time/place in the embryo; this is calledchange with time/place in the embryo; this is calleddifferentiationdifferentiation

DifferentiationDifferentiation occurs viaoccurs via c ell determinationc ell determination

Determination is the process of commitment of a cell lineDetermination is the process of commitment of a cell line

to a particular developmental pathwayto a particular developmental pathway

Some cells do not change; these areSome cells do not change; these are stem c ell stem c ell



DifferentiationDifferentiation

The ongoing differentiation results in theThe ongoing differentiation results in the

development of form and structure (i.e.development of form and structure (i.e.

morphogenesi smorphogenesi s) in the embryo) in the embryo

Occurs via changes inOccurs via changes in

Cell protein expressionCell protein expression

Signaling between cellsSignaling between cells

Cell migrationCell migration Interactions with the extracellular matrixInteractions with the extracellular matrix

Controlled death (Controlled death (apoptosi sapoptosi s) of cells) of cells



Fertilization

Fertilization

The first step in development of a newThe first step in development of a new

individual is fertilizationindividual is fertilization

Is the union of a (usually) tiny sperm and anIs the union of a (usually) tiny sperm and an

(usually) enormous ovum to form a(usually) enormous ovum to form a zy gotezy gote

Determines the sex of the offspring inDetermines the sex of the offspring in

mammalsmammals and many other animalsand many other animals Stimulates changes in the egg that allowStimulates changes in the egg that allow

developmentdevelopment

May be divided into four stepsMay be divided into four steps



Fertilization: Four Major Fertilization: Four Major

StepsSteps1.1. Sperm contacts the eggSperm contacts the egg

2.2. Sperm or its nucleus enters the eggSperm or its nucleus enters the egg

3.3. Egg becomes activated and developmentalEgg becomes activated and developmental

changes beginchanges begin

4.4. Sperm and egg nuclei fuseSperm and egg nuclei fuse



FertilizationFertilization



Events from Ovulation toEvents from Ovulation to

ImplantationImplantation



ImplantationImplantation The embryo implants in the wall of the uterusThe embryo implants in the wall of the uterus

on about the 7th day of developmenton about the 7th day of development Trophoblast secretes enzymes that locallyTrophoblast secretes enzymes that locally

erode the uterineerode the uterine wallwall1212--day Humanday Human

EmbryoEmbryo



PlacentationPlacentation

Formation of the placenta occurs from 11 Formation of the placenta occurs from 11

days to 12 weeksdays to 12 weeks

Extensions of syncytiotrophoblast (chorionicExtensions of syncytiotrophoblast (chorionicvilli) into endometrium by digestion & growthvilli) into endometrium by digestion & growth

of ³roots´ of tissueof ³roots´ of tissue

Villi become surrounded by pools of maternalVilli become surrounded by pools of maternal

blood that merge to form placental sinusblood that merge to form placental sinus blood stimulates rapid growth of chorionic villiblood stimulates rapid growth of chorionic villi

Mesenchyme grows into chorionic villi to formMesenchyme grows into chorionic villi to form

embryonic blood vessels in the villiembryonic blood vessels in the villi



The PlacentaThe Placenta Once fully developed is discOnce fully developed is disc

of tissue 20 cm in diameter of tissue 20 cm in diameter and 3 cm thickand 3 cm thick

Surface facing fetus isSurface facing fetus is

smooth & connected tosmooth & connected to

fetus by umbilical cordfetus by umbilical cord Uterine surface consists of Uterine surface consists of

villi and decidua basalis region of endometriumvilli and decidua basalis region of endometrium

Fetal & maternal blood does not mixFetal & maternal blood does not mix

Placental conductivity increases as villi grow since their Placental conductivity increases as villi grow since their membranes become thinner membranes become thinner

substances pass through by diffusion, facilitatedsubstances pass through by diffusion, facilitated

diffusion, active transport and receptor diffusion, active transport and receptor--mediatedmediated

endocytosisendocytosis



EmbryonicEmbryonic

MembranesMembranes

Amnion is transparent sac filled with fluidAmnion is transparent sac filled with fluid

protects embryo from trauma, temperature changes,protects embryo from trauma, temperature changes,

adhesions and provides freedom of movementadhesions and provides freedom of movement

forms from maternal plasma filtrate & fetal urineforms from maternal plasma filtrate & fetal urine

at term, amnion contains 700 to 1000 mL of fluidat term, amnion contains 700 to 1000 mL of fluid

Yolk sac hangs from ventral side of embryoYolk sac hangs from ventral side of embryo

contribute to GI tract, blood cells and germ cellscontribute to GI tract, blood cells and germ cells Allantois is foundation of umbilical cord & urinary bladder Allantois is foundation of umbilical cord & urinary bladder

Chorion is outermost membrane formed of villiChorion is outermost membrane formed of villi

forms fetal portion of the placentaforms fetal portion of the placenta



EmbryonicEmbryonic

MembranesMembranes



Pronuclear fusionPronuclear fusion



Blocks

ToP

olyspermyB

locksT

oP

olyspermy F ast block to pol yspermy F ast block to pol yspermy involves egg plasma membrane actioninvolves egg plasma membrane action

potential, prevents additional sperm from enteringpotential, prevents additional sperm from entering

The slow block to polyspermy involves the cortical reactionThe slow block to polyspermy involves the cortical reaction

Calcium ion entry causes fusion of largeCalcium ion entry causes fusion of large c orti c al granulesc orti c al granules

with plasma membrane that release digestive enzymeswith plasma membrane that release digestive enzymes The acellular The acellular v itelline membranev itelline membrane (not a plasma membrane(not a plasma membrane

but extracellular matrix) lifts away from the plasmabut extracellular matrix) lifts away from the plasmamembrane due to the digestive activity and local increase inmembrane due to the digestive activity and local increase inionic strength from the cortical granule contentsionic strength from the cortical granule contents

Forms aForms a fertili z ation env elopefertili z ation env elope that hardensthat hardens

In mammals, the zona pellucida sperm receptors areIn mammals, the zona pellucida sperm receptors aremodified to prevent further entry of spermmodified to prevent further entry of sperm

Some organisms do not block polyspermy.Some organisms do not block polyspermy.

Some amphibians degrade the supernumery spermSome amphibians degrade the supernumery sperm



CleavageCleavage During cleavage the zygote divides, giving rise toDuring cleavage the zygote divides, giving rise to

many cellsmany cells

The ovum contributes the majority of the zygoteThe ovum contributes the majority of the zygotecytoplasmcytoplasm

Both gametes contribute equal numbers of Both gametes contribute equal numbers of

chromosomeschromosomes Cleavage is a series of rapid mitotic division notCleavage is a series of rapid mitotic division not

accompanied byaccompanied by significant cell growthsignificant cell growth

The zygote forms a two celled embryo, andThe zygote forms a two celled embryo, andcontinues divisions to form a ball of 32 cells calledcontinues divisions to form a ball of 32 cells called

thethe morulamorula TheThe morulamorula continues divisions to form the hollowcontinues divisions to form the hollow

blastula with up to several hundred cellsblastula with up to several hundred cells

The cells are calledThe cells are called blastomeresblastomeres

The cavity of the blastula is theThe cavity of the blastula is the blastoc oel blastoc oel



Patterns Of CleavagePatterns Of Cleavage

The pattern of cleavage is affected by the yolkThe pattern of cleavage is affected by the yolk

Isolecithal eggs have a uniform yolk distributionIsolecithal eggs have a uniform yolk distribution

Simple chordates and most invertebrates have isolecithal eggsSimple chordates and most invertebrates have isolecithal eggs

Isolecithal eggs typically have holoblastic cleavageIsolecithal eggs typically have holoblastic cleavage

The daughter cells completely separate during cleavageThe daughter cells completely separate during cleavage Radial cleavage is typical of deuterostomes: echinoderms andRadial cleavage is typical of deuterostomes: echinoderms and

AmphioxusAmphioxus

First division is vertical; second division is at right anglesFirst division is vertical; second division is at right angles

Third division is horizontal at right angles to the first and formsThird division is horizontal at right angles to the first and forms

an 8 cell embryo with 4 above and 4 cells below the lastan 8 cell embryo with 4 above and 4 cells below the lastdivision planedivision plane

Spiral cleavage is typical of protostomes: annelids and molluscsSpiral cleavage is typical of protostomes: annelids and molluscs

After first two divisions the plane of cleavage tilts and diagonalAfter first two divisions the plane of cleavage tilts and diagonalto the polar axisto the polar axis



Cleavage an

d

Cleavage an

d Gastrulation inGastrulation in

AmphioxusAmphioxus

RadialRadialcleavagecleavage

Very similar Very similar

to the seato the sea

star star



Yolk Content Is ImportantYolk Content Is Important

Yolk provides energy for egg developmentYolk provides energy for egg development The more metabolically active end of the cell is the animal pole,The more metabolically active end of the cell is the animal pole,

which contains less yolkwhich contains less yolk

Amphibian eggs contain moderate amounts of yolk; calledAmphibian eggs contain moderate amounts of yolk; calledmesolec ithal mesolec ithal

Undergo holobastic cleavage but the divisions areUndergo holobastic cleavage but the divisions are

concentrated in the animal end of the egg (below, frog)concentrated in the animal end of the egg (below, frog)



Telolecithal EggsTelolecithal Eggs T elolec ithal T elolec ithal eggs have much yolk concentrated at theeggs have much yolk concentrated at the

vegetal polevegetal pole of the eggof the egg

Eggs of reptiles and birds are highly telolecithalEggs of reptiles and birds are highly telolecithal

Cell division takes place in theCell division takes place in the blastodi sc blastodi sc

Division isDivision is meroblasti c meroblasti c ; cells do not completely; cells do not completely

separate from each other and remain attached,separate from each other and remain attached,

at least initially, to the yolk massat least initially, to the yolk mass

In birds and some reptiles, the blastodisc splits intoIn birds and some reptiles, the blastodisc splits into

thethe epiblast epiblast (upper) and(upper) and hy poblast hy poblast (lower, nearest(lower, nearest

the yolk), separated by the blastocoelthe yolk), separated by the blastocoel



Cleavage in aCleavage in a

Bir d EmbryoBir d Embryo



Developmental DeterminantsDevelopmental Determinants

Cleavage may distributeCleavage may distribute dev elopmental determinant sdev elopmental determinant sin addition to changing the yolk distributionin addition to changing the yolk distribution

Cleavage provides building blocks for developmentCleavage provides building blocks for development

The unequal distribution of cytoplasm of the zygoteThe unequal distribution of cytoplasm of the zygoteresults in blastomeres with different cytoplasmicresults in blastomeres with different cytoplasmiccompositioncomposition

M osai c dev elopment M osai c dev elopment is a rigid developmental patternis a rigid developmental pattern

R egulati v e dev elopment R egulati v e dev elopment is a result of homogeneousis a result of homogeneous

cytoplasm, and cells produced by cleavage arecytoplasm, and cells produced by cleavage areequivalentequivalent

Most animals have developmental patternsMost animals have developmental patternssomewhere between these two extremessomewhere between these two extremes



CytoplasmicCytoplasmic

Determinants In theDeterminants In the

Frog

Egg

Frog

Egg

Determinants that are held in theDeterminants that are held in theegg are transferred to the zygoteegg are transferred to the zygote

In amphibians, fertilizationIn amphibians, fertilizationcauses a movement of thecauses a movement of thecortical cytoplasm, revealingcortical cytoplasm, revealing

lighter underlying cytoplasmlighter underlying cytoplasm The lighter gray cytoplasm isThe lighter gray cytoplasm is

called the gray crescentcalled the gray crescent

This region is bisected by theThis region is bisected by thefirst division, causing leftfirst division, causing left--rightrightsidedness of the future embryosidedness of the future embryo

Cells developing from the area of Cells developing from the area of the gray crescentthe gray crescent become thebecome thedorsal portion of the embryodorsal portion of the embryo

If cleavage is experimentallyIf cleavage is experimentallyforced to exclude the greyforced to exclude the grey

crescent, no dorsalizationcrescent, no dorsalization



GastrulationGastrulation

The blastula develops a hole in one end and cellsThe blastula develops a hole in one end and cellsstart to migrate into the hole; this forms thestart to migrate into the hole; this forms the gastrulagastrula

The process is calledThe process is called gastrulationgastrulation

The gastrula is a threeThe gastrula is a three--layered embryolayered embryo

The pattern of gastrulation is affected by the amountThe pattern of gastrulation is affected by the amountof yolkof yolk

The cells at the vegetal pole invaginate, initiatingThe cells at the vegetal pole invaginate, initiatinggastrulationgastrulation

The opening of the archenteron is the blastoporeThe opening of the archenteron is the blastopore

The vegetal pole invaginates and meets theThe vegetal pole invaginates and meets theopposite wall,opposite wall, obliterating the blastocoelobliterating the blastocoel

The archenteron is the newly formed cavityThe archenteron is the newly formed cavity

The blastopore is the opening of the archenteron,The blastopore is the opening of the archenteron,

and becomes the anus in deuterostomesand becomes the anus in deuterostomes



Gastrulation in a FrogGastrulation in a Frog

EmbryoEmbryo



Gastrulation in Bir dsGastrulation in Bir ds

In birds, theIn birds, the epiblast c ell sepiblast c ell s form the primitive streak, withform the primitive streak, withthethe primitive groove serving as the functionalprimitive groove serving as the functionalequivalent of theequivalent of the bblastoporelastopore

Cells migrate centrally, and dive into the streak, to turnCells migrate centrally, and dive into the streak, to turnunder the outermost layer of cells and move laterallyunder the outermost layer of cells and move laterallyand anteriorly inside the developing embryoand anteriorly inside the developing embryo

NoNo ar c henteronar c henteron is formedis formed

H ensen¶ s node

H ensen¶ s node is the site of cells that will form theis the site of cells that will form themesodermallymesodermally--derivedderived notoc hord notoc hord

Cells sink into the interior and move under theCells sink into the interior and move under theepiblast to form an extension from the nodeepiblast to form an extension from the node



Gastrulation in Bir dsGastrulation in Bir ds



OrganogenesisOrganogenesis Organogenesi sOrganogenesi s is the formation of the organsis the formation of the organs

Arises from the layering of cells that occurs during gastrulationArises from the layering of cells that occurs during gastrulation

The layers areThe layers are germ lay er sgerm lay er s; they have specific fates in the; they have specific fates in thedeveloping embryo:developing embryo:

E ndodermE ndoderm

The innermost layer The innermost layer

Goes on to form the gutGoes on to form the gut

M esodermM esoderm

In the middleIn the middle

Goes on to form the muscles, circulatory system, bloodGoes on to form the muscles, circulatory system, bloodand many different organsand many different organs

E c todermE c toderm The outermostThe outermost

Goes on to form the skin and nervous systemGoes on to form the skin and nervous system



Organogenesis Begins WithOrganogenesis Begins With

Development of the Nervous SystemDevelopment of the Nervous System

The nervous system is the firstThe nervous system is the firstorgan system to developorgan system to develop

The notochord grows andThe notochord grows andinduces overlying ectoderm toinduces overlying ectoderm toform the neural plateform the neural plate

Cells of the neural plate fold toCells of the neural plate fold toform the neural groove and theform the neural groove and thesurrounding neural foldssurrounding neural folds

The neural folds fuse, forming aThe neural folds fuse, forming ahollow neural tubehollow neural tube

The anterior portion forms theThe anterior portion forms thebrain; the rest forms the spinalbrain; the rest forms the spinalcordcord

Right, neural fold formation in theRight, neural fold formation in thehuman embryohuman embryo



The Neural CrestThe Neural Crest

TheThe neural c rest neural c rest is a critical structure that guides formation of is a critical structure that guides formation of several organ systemsseveral organ systems

The neural crest forms on either side of the point of fusionThe neural crest forms on either side of the point of fusion

Its cells migrate to form the dorsal root ganglia, theIts cells migrate to form the dorsal root ganglia, thepostganglioni c sy mpatheti c postganglioni c sy mpatheti c neuronsneurons, many sense organs, many sense organsand all pigmentand all pigment--forming cellsforming cells

Blocks of mesoderm calledBlocks of mesoderm called somitessomites form on the outside of form on the outside of the neural tube, become the vertebrae and associated partsthe neural tube, become the vertebrae and associated partsof the segmented body axisof the segmented body axis

Other organs are stimulated to form as a result, in part of neuralOther organs are stimulated to form as a result, in part of neuralcrest cell movements and differentiationcrest cell movements and differentiation

TheThe trac heatrac hea grows from the gut and lungs develop from itgrows from the gut and lungs develop from it TheThe phar y ngeal pouc hesphar y ngeal pouc hes grow laterally from the pharynxgrow laterally from the pharynx

Branc hial groov esBranc hial groov es meet the pharyngeal pouches and formmeet the pharyngeal pouches and formbranc hial ar c hesbranc hial ar c hes, important in many structures of the head, important in many structures of the head

The pharyngeal and branchial grooves form theThe pharyngeal and branchial grooves form the gill slit sgill slit s andandgills in aquatic vertebratesgills in aquatic vertebrates



Formation of the HumanFormation of the Human

HeartHeart The heart is derived from the fusion of bloodThe heart is derived from the fusion of blood

vessels in the early embryovessels in the early embryo

At first it is merely a single atrium and singleAt first it is merely a single atrium and singleventricleventricle

Torsion brings the atrium anterior to theTorsion brings the atrium anterior to theventricle and partitions form that divide theventricle and partitions form that divide theatrium and ventricle into left and rightatrium and ventricle into left and rightchamberschambers



Formation Of the Visceral OrgansFormation Of the Visceral Organs

Digestive tract formation starts as a simpleDigestive tract formation starts as a simple

tube separated in the middle by the yolk stalktube separated in the middle by the yolk stalk

Separates into foregut and hindgutSeparates into foregut and hindgut

Liver, pancreas and trachea are hollowLiver, pancreas and trachea are hollow

outgrowths from the gutoutgrowths from the gut

Human, 5th week embryo



TwinTwinss Dizygotic twinsDizygotic twins

2 eggs are ovulated and fertilized2 eggs are ovulated and fertilized

no more similar than any other siblingsno more similar than any other siblings

multiple ovulation can produce any number of offspringmultiple ovulation can produce any number of offspring

Monozygotic twinsMonozygotic twins

single egg is fertilized and embryoblast divides in twosingle egg is fertilized and embryoblast divides in two genetically identical siblings (controversial concept)genetically identical siblings (controversial concept)

must be same sexmust be same sex

triplets and quadruplets occasionally occur triplets and quadruplets occasionally occur



Ectopic PregnancyEctopic Pregnancy

Blastocyst implants somewhere other than uterusBlastocyst implants somewhere other than uterus

1 out of 300 pregnancies1 out of 300 pregnancies

most cases occur in uterine tube (tubal pregnancy)most cases occur in uterine tube (tubal pregnancy)

occurs because of tubal obstruction from previous pelvicoccurs because of tubal obstruction from previous pelvicinflammations, repeated abortions or tubal surgeryinflammations, repeated abortions or tubal surgery

Tube can not expand enough & ruptures by 12 weeksTube can not expand enough & ruptures by 12 weeks

conceptus may reimplant in abdominopelvic cavityconceptus may reimplant in abdominopelvic cavity

anywhere it finds an adequate blood supplyanywhere it finds an adequate blood supply

usually requires an abortionusually requires an abortion

9% of abdominal pregnancies result in live birth9% of abdominal pregnancies result in live birth

by cesarian sectionby cesarian section



Embryonic DevelopmentEmbryonic Development



Human Fetus at TenHuman Fetus at Ten

WeeksWeeks



ExtraembryonicExtraembryonic

MembranesMembranes



Human BlastocystHuman Blastocyst



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Oleh :Drs. Sofy Permana, MSc., DSc.

FMIPA-BIOLOGI

UNIVERSITAS BRAWIJAYA

CIRI-CIRI MANUSIA BERDASARKAN USIA



Human Prenatal DevelopmentHuman Prenatal Development

Gestation lasts 266 days from fertilization to birthGestation lasts 266 days from fertilization to birth Development begins in the oviductDevelopment begins in the oviduct

About 24 hours after fertilization, the zygoteAbout 24 hours after fertilization, the zygotehas divided to form a 2has divided to form a 2--celled embryocelled embryo

The embryo passes down the oviduct by ciliaThe embryo passes down the oviduct by cilia

and peristalsisand peristalsis TheThe z ona pelluc idaz ona pelluc ida has dissolved by the 5thhas dissolved by the 5th

day, when the embryo enters the uterusday, when the embryo enters the uterus

The embryo floats free for several days,The embryo floats free for several days,nourished by fluids from glands in the uterinenourished by fluids from glands in the uterinewallwall

At this point, it is called aAt this point, it is called a blastocyst blastocyst

TheThe trophoblast trophoblast forms theforms the c horionc horion and amnionand amnion

TheThe inner c ell massinner c ell mass forms the embryo itself forms the embryo itself



Embryonic Stage or WeeksEmbryonic Stage or Weeks

2to 9

2to 9

Begins when all 3 primary germ layers areBegins when all 3 primary germ layers are

presentpresent

Conceptus forms a set of membranes externalConceptus forms a set of membranes externalto the embryoto the embryo

Embryo begins receiving its nutrients from theEmbryo begins receiving its nutrients from the

placentaplacenta

Germ layers differentiate into organs and organGerm layers differentiate into organs and organsystemssystems

presence of organs marks the beginning of fetalpresence of organs marks the beginning of fetal

stagestage



22ndnd and 3and 3r dr d TrimestersTrimesters

In the second trimester In the second trimester

Fetus moves freelyFetus moves freely

Heart can be heard with a stethoscopeHeart can be heard with a stethoscope

µQuickening¶ movements felt by the mother µQuickening¶ movements felt by the mother

If born at 24 weeks, the fetus has a 50% chance of survivalIf born at 24 weeks, the fetus has a 50% chance of survival

Brain not yet able to support breathingBrain not yet able to support breathing

Kidneys and lungs are immatureKidneys and lungs are immature

In the third trimester In the third trimester

Fetus grows rapidlyFetus grows rapidly

Final differentiation of organs and tissuesFinal differentiation of organs and tissues

Grasping and sucking reflexes activeGrasping and sucking reflexes active

If born before 37 wks, is considered premature,If born before 37 wks, is considered premature, but has abut has agood chance of surviving if born after 30 weeksgood chance of surviving if born after 30 weeks

FullFull--term baby weighs about 6000 g and is 52 cm longterm baby weighs about 6000 g and is 52 cm long



ImplantationImplantation The embryo implants in the wall of the uterusThe embryo implants in the wall of the uterus on about the 7thon about the 7th

day of developmentday of development Trophoblast secretes enzymes that locally erode the uterineTrophoblast secretes enzymes that locally erode the uterine wallwall



1212--day Human Embryoday Human Embryo



The PlacentaThe Placenta TheThe plac entaplac enta is the site of nutrient, gas, and wasteis the site of nutrient, gas, and waste

exchangeexchange

Secretes hormones that maintain pregnancySecretes hormones that maintain pregnancy

T rophoblast T rophoblast cells releasecells release human c horioni c human c horioni c

gonadotropingonadotropin (hCG) which signals the corpus(hCG) which signals the corpusluteum to enlarge and produce progesteroneluteum to enlarge and produce progesterone

The placenta develops from the embryonic chorionThe placenta develops from the embryonic chorionand maternaland maternal uterine tissueuterine tissue

C horioni c v illi C horioni c v illi are formed from theare formed from the c horionc horion, and, and

project into theproject into the endometriumendometrium of the uterusof the uterus TheThe umbili c al c ord umbili c al c ord , containing, containing two umbili c al two umbili c al

arteriesarteries andand one umbili c al v einone umbili c al v ein connects theconnects theembryo and the placentaembryo and the placenta



Development of theDevelopment of the

PlacentaPlacenta



ExtraembryonicExtraembryonic

MembranesMembranes



HumanHuman

FetusFetusat Tenat Ten

WeeksWeeks



Organ DevelopmentOrgan Development Begins during the first trimester Begins during the first trimester

Gastrulation occurs during the 2nd and 3d weeks, followedGastrulation occurs during the 2nd and 3d weeks, followed

byby neurulationneurulation (formation of the neural tube)(formation of the neural tube)

The heart beats spontaneously after 3.5 weeksThe heart beats spontaneously after 3.5 weeks

After the first two months of development, the products of After the first two months of development, the products of

conception are called aconception are called a fetusfetus At the end of the first trimester (first 3 months of development)At the end of the first trimester (first 3 months of development)

Fetus can be recognized as a humanFetus can be recognized as a human

~56 mm long, and ~14 g~56 mm long, and ~14 g

The sexes can be differentiatedThe sexes can be differentiated

Ears, eyes becoming wellEars, eyes becoming well--developed,developed,

Skeleton starting to developSkeleton starting to develop

Notochord replaced with the developing vertebral columnNotochord replaced with the developing vertebral column

Moves, µbreathes¶, makes sucking motions with thumbMoves, µbreathes¶, makes sucking motions with thumb



The Neonate or NewbornThe Neonate or Newborn

Transitional periodTransitional period

first 6first 6--8 hours heart & respiratory rate increase & body8 hours heart & respiratory rate increase & body

temperature fallstemperature falls

periods of sleeping & gagging on mucus & debrisperiods of sleeping & gagging on mucus & debris

feed every 3 to 4 hours during 6 week neonatal periodfeed every 3 to 4 hours during 6 week neonatal period

Respiratory adaptations of newbornRespiratory adaptations of newborn

onset of breathing due to CO2 accumulationonset of breathing due to CO2 accumulation

great effort to inflate lungs for first few breathsgreat effort to inflate lungs for first few breaths Immunological adaptationImmunological adaptation

near adult levels of IgG through placenta for 6 monthsnear adult levels of IgG through placenta for 6 months

protection from most infectious diseases except whooping coughprotection from most infectious diseases except whooping cough

IgA in breast milk protects from gastroenteritisIgA in breast milk protects from gastroenteritis



Neonate Adapts Rapidly at BirthNeonate Adapts Rapidly at Birth

In the uterus the fetus was provided all it neededIn the uterus the fetus was provided all it needed

When born, the neonate must adapt to its new environment andWhen born, the neonate must adapt to its new environment andstart to provide some of what it needs, itself start to provide some of what it needs, itself

TheThe initial breathing responseinitial breathing response of the neonate is initiated byof the neonate is initiated bythe accumulation of carbon dioxidethe accumulation of carbon dioxide

Breathing initiates with the rapid generation and release of Breathing initiates with the rapid generation and release of pulmonar y surfac tant pulmonar y surfac tant , which lowers the surface tension,, which lowers the surface tension,allowing the first breath to be takenallowing the first breath to be taken

Breathing increases blood flow through the pulmonary circuitBreathing increases blood flow through the pulmonary circuit

Blood from the right ventricle flows through the largeBlood from the right ventricle flows through the largepulmonary circuit blood vesselspulmonary circuit blood vessels

Blood originally (Blood originally (in uteroin utero) bypassed the pulmonary circuit by) bypassed the pulmonary circuit bypassing through a hole in the heart wall between the rightpassing through a hole in the heart wall between the rightatrium and left atrium, called theatrium and left atrium, called the foramen ov aleforamen ov ale and via aand via ashut from the pumonary artery and aortashut from the pumonary artery and aorta

The foramen ovale and the shunt close shortly after birthThe foramen ovale and the shunt close shortly after birth



Environmental FactorsEnvironmental Factors Environmental factors affect the embryoEnvironmental factors affect the embryo

Prenatal development is greatly affected by anythingPrenatal development is greatly affected by anything

circulating in the maternal bloodcirculating in the maternal blood

The embryo is most susceptible to harm during the firstThe embryo is most susceptible to harm during the first ttrimester rimester

Alcohol abuse causes distinct changes in the fetus, is a distinctAlcohol abuse causes distinct changes in the fetus, is a distinctset of effects, called fetal alcohol syndromeset of effects, called fetal alcohol syndrome

Thalidomide was a tranquilizer used widely in the 1950s until itThalidomide was a tranquilizer used widely in the 1950s until it

was learned that it had serious sidewas learned that it had serious side--effects and caused fetaleffects and caused fetal

abnormalitiesabnormalities

About 5% of newborns in the United States have a clinicallyAbout 5% of newborns in the United States have a clinicallysignificant birth defect, accounting for about 15% of deathssignificant birth defect, accounting for about 15% of deaths of of

newbornsnewborns

Sonograms may help diagnose defects and position of the fetusSonograms may help diagnose defects and position of the fetus



Multiple BirthsMultiple Births

Sometimes the embryo splits at the twoSometimes the embryo splits at the two--cell stagecell stage

Each isEach is totipotent totipotent ±± can give rise to an individualcan give rise to an individual

If both live, give rise toIf both live, give rise to identi c al identi c al , or , or monozy goti c, twinsmonozy goti c, twins

Occasionally give rise toOccasionally give rise to c onjoined twinsc onjoined twins which share one or which share one or more body partsmore body parts

F raternal F raternal , or , or di zy goti c, twins di zy goti c, twins are the result of two eggs ovulatingare the result of two eggs ovulating

and being fertilizedand being fertilized

Fertilized by different sperm: are different geneticallyFertilized by different sperm: are different genetically

Different sex is possible: not so with identical twins (why?)Different sex is possible: not so with identical twins (why?)

Similar situations can occur tripletsSimilar situations can occur triplets

Multiple births due to in vitro methods are NOT identical siblingsMultiple births due to in vitro methods are NOT identical siblings

P tP t



PrematurePremature

InfantsInfants

Infants born weighing under 5.5 lbs.Infants born weighing under 5.5 lbs.

Respiratory system born before 7 months suffer fromRespiratory system born before 7 months suffer from

respiratory distress syndromerespiratory distress syndrome

insufficient surfactant causing alveolar collapse withinsufficient surfactant causing alveolar collapse with

exhalationexhalation

Thermoregulatory problems due to undevelopedThermoregulatory problems due to undeveloped

hypothalamushypothalamus ---- keep in incubator keep in incubator

Digestive system not well developed must be fed lowDigestive system not well developed must be fed low--fatfat

formula instead of breast milkformula instead of breast milk Immature liver fails to synthesize plasma proteinsImmature liver fails to synthesize plasma proteins

edema, deficiency of clotting & jaundice from bileedema, deficiency of clotting & jaundice from bile



AgingAging

Aging is not a uniform processAging is not a uniform process

Results in decreased function in the organ systemsResults in decreased function in the organ systems

Different organ systems age at different ratesDifferent organ systems age at different rates

The homeostatic response to stress decreases during agingThe homeostatic response to stress decreases during aging

The model of The model of c ellular ageing c ellular ageing describes the loss of ability todescribes the loss of ability to

divide seen in older cellsdivide seen in older cells

This process may be due to the loss of the production of This process may be due to the loss of the production of

telomerasetelomerase

Apoptosi s

Apoptosi s, which is genetically programmed cell death, may, which is genetically programmed cell death, mayalsoalso contribute to the changes seen during agingcontribute to the changes seen during aging

It is not the apoptosis process itself that leads to ageing;It is not the apoptosis process itself that leads to ageing;

defects in apoptosis may lead to abnormalities of functiondefects in apoptosis may lead to abnormalities of function



Thank you very much Thank you very much

Perkemb_ Hwn & Mns-olympic_sofy08-Edit

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