An overview of Muir Wood Adolescent and Family Services teen treatment programs.
Unit-2 FETALDEVELOPMENT.pdf for IV year B ScN
1. B.Sc. DEGREE COURSE IN NURSING (BASIC)
Midwifery and Obstetrical Nursing
Unit: II - REVIEW OF ANATOMY AND
PHYSIOLOGY OF FEMALE REPRODUCTIVE
SYSTEM AND FETAL DEVELOPMENT
Fetal Development
DR. LATHA VENKATESAN,
PRINCIPAL
2. Learning Objectives
• Enumerate Stages of fetal development
• Outline the cell stage of zygote
• Describe the pre embryonic development
• Explain the embryonic development
• Discuss the development of fetus with gestation
week
• Enlist the development of each system in the fetus
• List the functions of placenta
3. Stages of fetal development
• Begins with fertilisation and
lasts about 3 days,zygote
develops and it implants into
the endometrium(upto3rd
weeks).
PRE-EMBRYONIC-
• Begins with the 4th of the
gestation and ends with the
8th of gestation.
EMBRYONIC-
• After 8th weeks till birth
continues to develop.
FETAL STAGE-
4. Day 4:
16-32 cell stage solid ball of cells = morula
Day 3: 6-
12 cell stage
can test at this stage for genetic
diseases if done by IVF
Day 2:
2nd cleavage 4 cell stage
Day 1:
1st cleavage 2 cell stage
Human fetal development
6. 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!
7. Human fetal developmental
• Days 10 - 14:
• 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
8. Pre embryonic stage
•Cleavage
• Morula-zygote undergoes mitotic division and
forms 2 cell stage after 30 hrs after fertilization
•Morula spends 3 days inside tube3 and enters into
uterus on 4 day as 16-64 cell stage.
Blastocyst : morula on 5 day is covered by film of
mucus.flui passses through the cannaliculi of zona
peellucida and spreads .
Zona hatching :lysis of zona pellucida and escape
of embryo is called zonahatching
9. Human fetal developmental
• Days 15 - 21:
• 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
14. 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
15.
16. Stages and Time Frames
• Ovum
• Zygote
• Morula
• Blastocyst
• Embryo
• Fetus
(Oh, Zee my baby eats
fast)
17. Implantation
• Implantation occurs in the endometrium of the anterior or
posterior wall of the body near the fundus on the sixth day
which corresponds to the 20 day of cycle
•Stages of Implantation
•Apposition
•Adhesion
•Penetration
•Invasion
19. Decidua
•Decidua is the endometrium of the pregnant
uterus
•Increased structural and secretory activity of
the endometrium that is brought about in
response to progestrone following implantation
is called decidual reaction.
20. Different portions of decidua
Decidua basalis or serotonia-
becomes the maternal surface of placenta at term.
Decidua capsularis or reflexa
Decidua vera or parietalis
21. Chorionic Villi
• proliferation of cytotrophoblast extend
into syncytiotrophoblast
• 12th day
Primary villi
• mesenchymal cord, derived from
cytotrophoblast, invade solid
trophoblast column
Secondary villi
• after angiogenesis occurs from
the mesenchymal cores in situ
Tertiary villi
• fetal blood vessels are functional &
placental circulation establish
17th day
22.
23. FETAL MEMBRANES
•Amnion-
•thin,tough inner membranes that lies the amniotic
sac.
•Chorion-
•closest to the uterus.
•Gives rise to the placenta
•Vascular projections called chorionic villi arise
from its periphery.
•Blood flows through developing network of
vessels as soon a the embryo’s heart begin to
beat.
29. 1 Month-4 weeks
• First Trimester
At the end of four weeks:
• Baby is 1/4 inch in length
• Heart, digestive system,
backbone and spinal cord
begin to form
• Placenta (sometimes called
"afterbirth") begins to develop
• The single fertilized egg is now
10,000 times larger than size
at conception
30. 8 Weeks
• First Trimester
At the end of 8 weeks:
• Baby is 1-1/8 inches long
• Heart is functioning
• Eyes, nose, lips, tongue, ears
and teeth are forming
• Penis begins to appear in boys
• Baby is moving, although the
mother can not yet feel
movement
31. 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
32. 12 Weeks
• First Trimester
At the end of 12 weeks:
• Baby is 2 1/2 to 3 inches long
• Weight is about 1/2 to 1 ounce
• Baby develops recognizable form.
Nails start to develop and earlobes
are formed
• Arms, hands, fingers, legs, feet
and toes are fully formed
• Eyes are almost fully developed
• Baby has developed most of
his/her organs and tissues
• Baby's heart rate can be heard at
10 weeks with a special instrument
called a Doppler
33. 16 Weeks
• Second Trimester
At the end of 4 months:
• Baby is 6 1/2 to 7 inches long
• Weight is about 6 to 7 ounces
• Baby is developing reflexes, such as
sucking and swallowing and may begin
sucking his/her thumb
• Tooth buds are developing
• Sweat glands are forming on palms and
soles
• Fingers and toes are well defined
• Sex is identifiable
• Skin is bright pink, transparent and
covered with soft, downy hair
• Although recognizably human in
appearance, the baby would not be able
to survive outside the mother's body
34. 20 Weeks of Gestation
• Second Trimester
At the end of 5 months:
• Baby is 8 to 10 inches long
• Weight is about 1 pound
• Hair begins to grow on baby's
head
• Soft woolly hair called lanugo will
cover its body. Some may
remain until a week after birth,
when it is shed.
• Mother begins to feel fetal
movement
• Internal organs are maturing
• Eyebrows, eyelids and
eyelashes appear
35. 24 Weeks
• Second Trimester
At the end of 6 months:
• Baby is 11 to 14 inches
long
• Weight is about 1 3/4 to 2
pounds
• Eyelids begin to part and
eyes open sometimes for
short periods of time
• Skin is covered with
protective coating called
vernix
• Baby is able to hiccup
36. 28 Weeks of gestation
• Third Trimester
At the end of 7 months:
• Baby is 14 to 16 inches long
• Weight is about 2 1/2 to 3 1/2
pounds
• Taste buds have developed
• Fat layers are forming
• Organs are maturing
• Skin is still wrinkled and red
• If born at this time, baby will be
considered a premature baby and
require special care
•
37. 32 Weeks of Gestation
• Third Trimester
At the end of 8 months:
• Baby is 16 1/2 to 18 inches long
• Weight is about 4 to 6 pounds
• Overall growth is rapid this month
• Tremendous brain growth occurs at
this time
• Most body organs are now
developed with the exception of the
lungs
• Movements or "kicks" are strong
enough to be visible from the
outside
• Kidneys are mature
• Skin is less wrinkled
• Fingernails now extend beyond
fingertips
38. 36 Weeks of gestation
Third Trimester
At the end of 9 months:
• Baby is 19 to 20 inches long
• Weight is about 7 to 7 1/2
pounds
• The lungs are mature
• Baby is now fully developed
and can survive outside the
mother's body
• Skin is pink and smooth
• Baby settles down lower in the
abdomen in preparation for
birth and may seem less
active
39. AMNIOTIC FLUID
Clear, yellowish fluid surrounding the developing
fetus.
Average amount 1000 ml.
Having < 300ml – Oligohydramnios,
associated with fetal renal abnormalities.
Having > 2 L – Hydramnios, associated with GI
and other malformations.
40. Functions of Amniotic Fluid
Protects Fetus
Controls
Temperature
Supports
Symmetrical
Growth
Prevents
Adherence to
amnion
Allows
Movement
Source of oral
fluid
Acts as a
excretion-
collection
repository
41. UMBILICAL CORD
Connecting link between fetus and placenta.
•Transports oxygen and nutrients to fetus from
the placenta and returns waste products from
the fetus to the placenta.
•Contains: 2 arteries and 1 vein supported by
mucoid material (wharton’s jelly) to prevent
kinking and knotting.
•Contains NO pain receptors.
43. PLACENTA- Functions
Produce protein hormones:
Human chorionic gonadotrophin
(HCG)- 8-10 days past conception,
is basis for pregnancy test
Progesterone
Estrogen
Human Placental
Lactogen
44. Placenta-Functions
•Sieve/filter – allows smaller particles through and
holds back larger molecules. Passage of
materials in either direction is effected by:
•Diffusion: gases, water, electrolytes
•Facilitated transfer: glucose, amino acids,
minerals.
•Pinocytosis: movement of minute particle
46. VIABILITY
• Capability of fetus to survive
outside uterus at the earliest
gestational age - 22-24 weeks
• Survival depends on:
• Maturity of fetal central
nervous system
• Maturity of lungs
47. RESPIRATORY SYSTEM
• Terminal SAC period - 24 Weeks to birth
• Growth of primitive alveoli
• Pulmonary surfactants produced
which act as wetting agents that
prevent alveolar walls from sticking
• Insufficient surfactant - RDS
• Lecithin/Sphingomyelin-Phospho Lipids
L/S Ratio
30-32 Weeks 1.2 : 1
35 Weeks 2:1 (MATURITY)
49. FETAL CIRCULATION
• Arteries in umbilical cord and
fetal body carry
deoxygenated blood.
• Vein in cord and those in
fetal body carry oxygenated
blood
• Ductus venosus connects
umbilical vein and inferior
vena cava; bypassing portal
circulation.
50. FETAL CIRCULATION
•Foramen Ovale allows
blood to flow from right
to left atrium,
bypassing lungs.
•Ductus Arteriosus
allows blood flow from
pulmonary artery to
aorta, bypassing fetal
lungs;
51. •HEPATIC SYSTEM
•Liver functions 4-6 weeks
•Full liver function after delivery
•MUSCULO-SKELETAL SYSTEM
•Bones and muscles develop by 4th week
•Fontanels – areas where >2 bones meet
•7-8 Weeks arms & leg movements
52. GASTROINTESTINAL SYSTEM
• Forms during 4th week
• Middle portion of the intestine
projects out into cord during 5th
week. Returns during 10th week.
If this does not occur-
Omphalocele present at birth
• Meconium – Dark green to black
tarry waste accumulated in the
fetal intestine near term
53. RENAL SYSTEM
•Kidneys form in 5th week and begin to function
4 weeks later.
•Voiding into amniotic fluid
•Low volume can show renal dysfunction
•Renal malformation can be diagnosed in utero.
•GFR is low at birth
54. NEUROLOGICAL SYSTEM
• Formed from the ectoderm
3rd week
• Respiratory effort
18 1/2 WKS
• Swallowing
12 1/2 WKS
• Sucking
29 WKS
• Fetal movement felt (Quickening)
16-20 WKS
55. ENDOCRINE SYSTEM
• Thyroid gland 1st to develop
• Insulin produced at 20 weeks
INTEGUMENTARY SYSTEM
• 7th week – Two layers of cells
• Vernix caseosa –Protects skin
• Lanugo – Fine hair
• 10th week – Fingernails, toenails
