INTEGRATED REPRODUCTIVE HEALTH

1. FERTILIZATION AND
FETAL DEVELOPMENT
MR. JONES H.M-MBA
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2. FERTILIZATION
• Fertilization occurs after ovulation and it takes
place in the Ampulla of the Fallopian tube.
• The male deposits about 300 million sperms in
the vagina after ejaculation, and only about
1000 to 3000 sperms reach the ovum.
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3. • The sperms propel themselves by the lashing
movement of the tail and move in the forward
direction.
• Out of these, some are destroyed by the
acidity of the vaginal fluid while some may fail
to reach the uterus because they cannot swim
against the fluid current.
• Those that reach the fallopian tubes retain
their fertilizing ability for at least 72hours.
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4. • During sexual intercourse, 2 to 5 ml of semen,
usually containing more than 300 million
sperm, is ejaculated into the vagina.
• By flagellar (wiggly) movement, the sperm
make their way through the fluids of the
cervical mucous, across the endometrium, and
into the fallopian tube to meet the descending
ovum in the ampulla of the fallopian tube .
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5. • Only one sperm is required for actual
fertilization, but the presence of many
increases the chances for one to penetrate.
• The union between ovum and sperm occurs in
the outer third of the fallopian tube.
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6. • The mature sperm (spermatozoon) that encounters
the ovum produces an enzyme called
Hyaluronidase which breakdowns the protective
protoplasm of the ovum in order to make
penetration of the cell a little easier.
• As soon as contact between the sperm head is
established, the two cells clamp together and the
cell membrane is sealed so that no other sperm is
allowed to penetrate the ovum.
• The body and tail of the sperm separate from the
head as soon as access to the ovum has been
gained (Sellers, 2010).
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7. PROCESS OF IMPLANTATION
(EMBEDMENT)
• After fertilization, the ovum is called zygote
which divides repeatedly into 2, 4, 8, 16 etc.
by the process called mitosis or
segementation, a solid mass of cells is formed
called morula.
• The morula reaches uterine cavity by the 4th
day after fertilization.
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8. • By the time of embedment the morula is now
called Blastocyst.
• The outer surface of the blastocyst becomes
covered with finger-like projections called
chorionic villi.
• Chorionic villi aid in the process of
implantation into the endometrium (decidua).
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9. • Villi also manufacture human chorionic
gonadotropin (HCG) which signal the corpus
luteum within the ovaries to continue
production of progesterone and estrogen to
prevent menstruation.
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10. • The outer covering (layer) of the blastocyst is
composed of cells called trophoblast (layer of
cells) and this trophoblast forms the placenta.
• On one aspect of the inner surface of the
blastocysts are inner cells which form the
foetus.
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11. • Implantation normally occurs in the upper,
posterior wall of the uterus.
• The point of implantation becomes the origin
for the placenta and umbilical cord.
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12. FORMATION OF THE DECIDUA
• If fertilization takes place there is increased
structural growth of the endometrium.
• The endometrium will become thick, soft,
vascular, and spongy in readiness for
embedment or implantation and maintenance
of a fertilized ovum.
• The endometrium is now called the decidua.
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13. LAYERS OF THE DECIDUA
There are 3 distinctive layers of the decidua.
1. Basal layer (inner most)
• Does not shade off after delivery,
regeneration of cells start from this layer.
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14. Spongy Layer (functional Layer)
• It is so called because it is like a sponge in
texture.
• It is found above the basal layer and is
composed of glands which are filled with
secretions.
• It prevents deep embedment of the villi.
• If embedment is beyond the spongy layer it
leads to retained placenta.
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15. Compact Layer
• Lies on top of the spongy layer and lines the
decidua of the endometrium.
• This is the first layer that the fertilized ovum
encounters when it enters the uterine cavity
as this layer is continuous with the lining of
the uterine tubes.
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16. GROWTH OF THE FOETUS
A. The Trophoblast
• It grows into finger like projections and
spreads into all directions in the
surrounding decidua.
• The trophoblast cells forms the placenta.
• As the trophoblasts cells proliferate or
multiply they are differentiated into 3
layers. 8/26/2019JONES H.M-MBA 16

17. THE BLASTOCYSTS
• While the trophoblast is developing into the
placenta which will nourish the fetus, the inner
cell mass is forming the fetus.
• The cells differentiate into 3 layers. Each of
which will form particular parts of the fetus.
• a. Ectoderm - This mainly forms the skin and
the nervous system.
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18. Mesoderm
• Forms bones and muscles.
• And also forms the heart, and blood vessels
including those that are in the placenta.
• Certain internal organs also originate from the
mesoderm.
Endoderm
• Forms mucus membranes and glands. 8/26/2019JONES H.M-MBA 18

19. • The three layers together are known as the
embryonic plate.
• Two cavities appear in the inner cell mass. One
on either side of the embryonic plate. The first
cavity is the Amniotic cavity and the second is
the York sac.
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20. Amniotic Cavity
• Lies on the side of the ectoderm.
• The cavity which is filled with fluid, and gradually enlarges and folds
round the embryo to enclose it.
• The amniotic forms from its lining.
• It swells out into the chorionic cavity.
Yolk Sac
• This lies on the side of the endoderm and provides nourishment for the
embryo until the trophoblast is sufficiently developed to take over.
• Part of it contributes to the formation of a primitive gut.
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21. THE PLACENTA
• This is an organ that originates from the
trophoblastic layer of the fertilized ovum.
• It links closely with the mother’s circulation to
carry out functions which the fetus is unable to
perform for itself during intra - uterine life.
• The survival of the fetus depends upon its
integrity and efficiency.
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22. THE PLACENTAL CIRCULATION
• Blood from the foetal heart circulates via the
foetus and is carried by the umbilical cord to
the placenta and subdivides until they
terminate in the chorionic villi which absorb
nutrients from the mothers’ blood and these
include glucose, amino acids, minerals etc.
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23. • The foetal GIT does not function nor do the
lungs inhale O2 therefore the placenta carries
out functions of the GIT, of the lungs and
functions of the kidneys.
• CO2 and other waste products are given off
into the mothers blood for excretion.
• Interchange of substances occurs by osmosis
and diffusion as well as selective reabsorption.
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24. • The replenished oxygenated blood returns to
the foetus via the umbilical vein.
• Therefore:
Umbilical vein: carries oxygenated blood
Umbilical artery: carries deoxygenated blood.
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25. THE PLACENTA AT TERM
SITE
• The placenta is normally situated in the upper uterine segment.
SHAPE
• It is a flat roughly circular structure.
SIZE
• It is approximately 20cm in diameter, 2 - 2.5 cm thick in the
centre but gets thinner towards the circumference.
WEIGHT
• 0.5 kg (500g) or 1/6th of the baby’s birth weight.
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26. SURFACES OF THE PLACENTA
These are two:
The maternal surface
• The maternal surface blood gives this surface a dark red
colour. Part of the basal deciduas will have been
separated with it.
The foetal surface
• The amnion covering the foetal surface of the placenta
gives it a white shinny appearance.
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27. FUNCTIONS OF THE PLACENTA
• Barrier: Not all substances pass through the
placenta
• Excretory: Excretes metabolic wastes
• Respiratory: O2 passes from mother blood to
babies, CO2 returns to mothers blood.
• Endocrine: Progesterone, oestrogen and human
chorionic gonadotrophin hormones, these
maintain the pregnancy
• Nutritive: Glucose, amino acids, iron, minerals
e.g. calcium
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28. THE FOETAL SAC
• Consist of a double membrane:
The chorion (outer)
The Amnion (Inner)
• The foetus and amniotic fluid are contained
within the sac which ruptures during labour to
permit the expulsion of the foetus and
amniotic fluid.
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29. AMNIOTIC FLUID
• It is clear pale straw coloured fluid in which the
foetus float.
• The amount increases with cyesis and range from
500 ml to 1500 ml.
Constituents of amniotic fluid
• 99% is water
• 1% are food substances and waste products mainly
minerals salts, urea and foetal urine. Lanugo from
skin of foetus, vernix caseosa, protein.
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30. FUNCTIONS OF AMNIOTIC FLUID
• It distends the amniotic sac and allows for the
foetal growth and free movement
• It prevents injury to the foetus
• It maintains constant temperature for the foetus
• Provides small amount of nutrients for the foetus
• In labour the amniotic fluid protects the placenta
and umbilical cord from the pressure of uterine
contraction or dilatation
• It helps in dilatation of the cervix where the
presenting part is poorly applied.
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31. THE UMBILICAL CORD
• The umbilical cord or funis extends from the
foetus to the placenta.
• Average length of the cord is 50 cm to 56 cm
• It is commonly inserted in the centre of the
foetal surface.
• It transmits the umbilical vessels; umbilical
vein (1) and umbilical arteries (2).
• The vessels are enclosed and protected by
wharton’s jelly.
• The entire cord is covered in a layer of amnion
continuous with that of the covering of the
placenta.
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32. FOETAL CIRCULATION
• Before birth there are 4 temporary structures in the
heart namely:
• Ductus venosus: Connects the umbilical vein to the
inferior vena cava.
• Foramen ovale: Opening between the right and left
atria.
• Ductus arteriosus: between pulmonary artery and
the descending aorta.
• Hypogastric arteries: Are branches of the right and
left internal iliac arteries enter the umbilical cord
carrying deoxygenated blood to the placenta.
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33. FOETAL DEVELOPMENT
Is considered according to the station
• At 3 weeks: Foetus is a grape size covered with
chorionic villi and features are unidentified, its
just a mass.
• End of 4 weeks
• It is like a pigeon egg in a sac and is about 7.5
cm long with the foundation of ears, eyes,
nose and there are small buds (protrusion) for
limbs. It weighs 1 gm.
• Heart beat can be heard by ultrasound.8/26/2019JONES H.M-MBA 33

34. • End of 8 weeks: It is a size of the hens egg.
The head is larger than other parts.
• At the end of 12 weeks: It is the size of the
goose egg and measures 10 cm in length and
60 g in weight.
• Centres of ossification are laid down in most
bones, finger and toe nails begin to form, sex
can be identified.
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35. • At the end of 16 weeks: Lanugo appears on
shoulder and back, nasal septum and palate
are fused, meconium is formed.
• The heart beat can be heard by foetal scope
and it is prominent in multiparous women.
• It measures 15 cm in length and weighs 150 –
170 g.
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36. By the end of 20 weeks
• There is lanugo all over the body, hair appears
on the head, the skin excretes greasy white
substance, it measures 20 cm in length and
weighs 300 – 400g.
• The foetal heart is heard on auscultation or
fetal scope in prime gravid.
• Quickeining occurs - the first movement the
foetus makes in utero.
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37. By end of 24 weeks
• The skin is wrinkled, the head is larger in
relation to the body.
• It measures about 30 cm long and weighs 600
– 700 g.
At the end of 28 weeks
• Vernix caseosa is formed, this is visible, foetus
moves freely in the amniotic fluid meconeum
is present, the length is 35 cm long and the
weight is 1000g. 8/26/2019JONES H.M-MBA 37

38. By the end of 35 weeks
• cartilage is formed in the ears.
• Soaked nails reach tips of finger the skin is
smooth free from wrinkles due to deposition
of subcutaneous fat.
• Testicles descend in the scrotum in males.
• The length is 45 cm and weight is 2500g.
At the end of 40 weeks
• The entire head is covered with hair toe nails
are well formed the length is 48 – 50 cm and
the weight should be 3200 – 3500g
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39. ABNORMALITIES OF THE UMBILICAL
CORD
Short cord:
• Is any cord less than 40 cm, but it could be as
short as 20 cm.
Dangers
• It delays or prevents descent of the fetus during
labour.
• Early separation of the placenta causing fetal
anoxia.
• The cord may snap which could result in fetal
anoxia.
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40. Very long cord:
• Some cords may be as long as 150 cm.
• Long cords may become wound to any part of the fetus
or even two – three times around the neck of the fetus
at birth.
• If too tight this will lead to reduction of blood flow to
the distal tissues which may lead to underdeveloped or
it may stop the blood flow which will cause withering of
the limbs even fetal death if wound around the neck or
body of the fetus.
• During delivery it can strangulate the fetus and cause
death.
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41. True knots in the cord
• This is caused by the fetus passing through a
loop of the cord and forming a knot on the
cord.
• This is most likely to occur in a long cord.
During delivery the cord may be drawn tight as
the fetus descends causing anoxia and fetal
death.
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42. ABNORMALITIES OF THE PLACENTA
Placenta oedema
• A large pale placenta may indicate that the mother has diabetes
mellitus.
• A large pale waterly placenta can be an indication of hydrops
fetalis due to rhesus iso immunization or due to some
pathological conditions of the fetal kidneys or pituitary gland or
due to maternal syphilis.
Meconeum stained ( yellow ) placenta and cord
• This staining is caused by meconeum being passed in utero, for
example intra uterine growth retardation due to periods of fetal
hypoxia.
• Yellow staining can also be due to high levels of bilirubin in liquor
amnii caused by rhesus iso immunization.
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43. THE END!
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