Download fetal development - Effingham County Schools

FETAL
DEVELOPMENT
FROM CONCEPTION TO BIRTH
Healthcare Science Technology 1
Mrs. Burgstiner,BSN
A. Fertilization: Sperm penetrates Egg
• Oocyte is released from the ovary and begins down the fallopian tube.
• Sperm enters the female reproductive tract through the vagina during
intercourse.
• About 300 million sperm cells enter the vagina but only about 1%
make it through the uterus to the fallopian tubes after approximately
10 hours
• One sperm then penetrates the oocyte (egg) through the zona
pellucida which is the membrane surrounding the oocyte (egg)
• Sperm then breaks apart inside egg: this helps to determine the sex of
the developing fetus by the DNA
• Zygote: joining of the sperm and ovum (egg ) to create new life or a
new cell.
• This completes the fertilization process.
B. Cleavage:(1.5-3 days post ovulation)
• Rapid Division of the Zygote into two cells, then 4
cells and so on and these cells are called blastomeres.
• This series of divisions occurs about one every 24
hours.
Then when the cell division reaches
10 – 32 cells it is called a Morula
The morula leaves the fallopian tube
and enters the uterus.
This takes place about 3-4 days
after fertilization.
C. Early Blastocyst: (4 days)
1. The Morula is now inside the
uterus.
2. Cell division continues until
a blastocele forms in the center
of the Morula.
3. Once the blastocele forms in the morula it is then called a
blastocyst and has a cavity in the middle.
4. Two types of cells are at work now:
A. Embryoblast: cells inside the blastocele.
B. Trophoblast: cells outside of blastocele
D. HCG Hormone is Released (5-6 d.)
• On around the 6th day: blastocyst hatches or is released
from zona pellucida (surrounding membrane)
• The trophoblast cells then secrete an enzyme Human
Chorionic Gonadatropin (HCG) that erodes the uterine wall
• This creates an implantation site on the inner uterine wall.
• Implantation to uterine wall: hormones are stimulated and
the ovary produces progesterone and the HCG continues
releasing as the blastocyst implants into the uterine wall.
• The blastocyst becomes swollen with new capillaries and
circulation begins between mother and fetus…this process
is necessary for pregnancy to continue.
E. Implantation is complete: 712 days)
1. The trophoblast cells continue to
engulf/destroy the uterine lining
stimulating new
capillary growth from the blood
pools they create.
2. This is when placental
circulation beginning)
3. Top layer of cells becomes the embryo
4. Lower layer : becomes the yolk sac.
ECTOPIC PREGNANCY
An Ectopic Pregnancy an
occur during implantation.
This is when the implantation
takes place outside of the
uterus….
Can take up to 16 weeks to
manifest. Surgery is required
in most cases to remove the
implanted fetus. Also known
as a tubal pregnancy).
F. Placental Attachment:
Chorionic Villus:“fingers” of the forming
placenta, that anchor the placenta to the
implantation site in the uterus.
The Embryo is attached by a connecting
stalk to the developing placenta by the
Umbilical cord.
This is a picture of the placenta
after delivery. The baby and the
placenta are both delivered….you
can see the umbilical cord here as
well.
G.Gastrulation begins: the 3
layers of the embryo
A narrow line of cells start to form and the future axis of
the embryo takes shape and marks the beginning of
gastrulation.
Gastrulation forms the three layers of the embryo from
which cells, tissues, organs and systems develop.
The 3 layers are:
Ectoderm
Mesoderm
Endoderm
The next slide will show you what these 3 layers become.
Ectoderm, Mesoderm and Endoderm
During gastrulation, three major cell lineages are being established. They are the Ectoderm (shown in the diagram as blue),
Mesoderm (red) and Endoderm (yellow). Following gastrulation, various cell lineages are derived from these three primary
cell types. For example, the Ectoderm gives rise to the epidermis and its derivatives such as nails, hair and teeth. On the other
hand, the Ectoderm also gives rise to the Central Nervous System.
G. Fetus at 2-3weeks
1/10 of an inch long
nervous system is developing
blood cells are developed
H. Fetus at 4 weeks
May float freely for 48 hours before implanting
Arm buds start to be evident
gets more of a curved appearance
eyes start to develop
implantation of to the uterus and placenta is
taking place
I. The Fetus at 5 weeks
•The nose starts to form
•Placental blood vessels form
•Endocardial (muscle) cells begins to form
the two heart tubes
J. The Fetus at 6 weeks
•1/2 inch long (floating in amniotic fluid)
•leg buds present
•spine is visible
•ears are forming
•at 6 weeks heart muscle starts to beat
•has rapid growth at this stage
•head/mouth/liver/intestines start to take
shape
K. The Fetus at 7 weeks
• 3/4 inches long
• Hand/fingers are formed and moving
•eye lens form
•skull bones are visible and growing
•sexual organs are forming
•brain waves have started
•muscles develop and get stronger
L. Fetus at 8-9 weeks old
Heart Development Ends
The brain can move muscles
Sexual organs are forming
Feet become more defined
Digits are separating on hands/feet
Toe/Finger joints are visible
As you can see the fetus is in its
own sac of amniotic fluid attached to
the mother by an umbilical cord
to the placenta where it gets all it’s
nourishment from. (Above are two
twin boy fetuses in separate sacs)
M. 10 Week Old Fetus
(2 1/2 months old) Now considered a fetus
• 1-2 inches long
•Has a stump for a tail’
• Is now very active
• Facial features developed
• Fingers/ Toes/ Hands/ Feet developed
•Internal Organs are functioning
• Nervous System is responsive: He/She can feel!
N. 11 Weeks old:
Now is 2 1/2 inches long
12 WEEKS(3 months)
•3 inches long
•umbilical
cord intact and
is fully
functional
14 WEEKS (3 1/2 months)
•3- 31/2 inches
•weight is 1 ounce
•muscles are
developing
•sex organs form
•eyelids form
•fingernails and toenails
•spontaneous
movement is observed
15-18 WEEKS
( 4-4 1/2 months)
•Sensory Organs
form at (15)
•(16) is turning
inside of MOM
•(18) 5 1/2 inches
•blinks, grasps,
moves mouth,
hair on head and
body is present
•all systems are
developed
•fetal respiration's
are occurring
•Must be at least
24 weeks to
survive outside of
womb
WEEK 22 (5 1/2 months)
•1/2 pound
•10 inches
long
•sweat glands
•external skin
is turning from
transparent to
opaque
WEEK 26
(6 1/2 Months
•Inhales and
exhales
•cries
•eyes are
completely
formed
•has tongue and
taste buds
•has a 50%
chance of
survival outside
of the womb
with intensive
Medical care
WEEK 30
(7 1/2 months)
(7 1/2 mo.)
•Is premature
if born
•But most do
well if born at
this time
•Girls fair
better than
boys because
their lungs are
more
developed.
FULL TERM (36 -40 weeks)
This is the end of
normal
gestation….
Baby is now able
to live outside of
the mother’s
womb.
PREMATURE BABIES
(born before 36 weeks)
•May or may not have developed well
enough
•This is where some birth defects can occur
•Difficult deliveries can cause birth trauma
leading to problems
•Drugs and Alcohol use can lead to
premature births.
•Stress or illness can cause premature birth
Premature baby at 28 weeks: 2 lbs.
Baby a year
Later:
Still not out
of NICU yet!
Genetic Problems
Chromosomal problems in the formation of
the fetus can cause genetic problems.
These children often have differences that
follow them throughout their
lives
Drug Abuse:
Is very detrimental at different stages of fetal
development..they cross the placenta and can
cause defects and addiction.