The document provides information on the development of the placenta and fetus. It discusses that the placenta develops from the trophoblastic layer of the blastocyst starting at 3 weeks after fertilization. The placenta establishes maternal-fetal circulation by 17 days and reaches maturity by the third trimester. It functions to transport oxygen, nutrients, and waste between the mother and fetus. Fetal development proceeds rapidly from the embryonic stage through the fetal stages, with all major organ systems developed by 8 weeks and the fetus gaining weight and physical features through the second and third trimesters.

1. DEVELOPMENT
OF
PLACENTA & FETUS
PRESENTED BY:
Ms. Satnam Kaur Mand

2. INTRODUCTION
• The Placenta is partly fetal and partly
maternal in origin.
• It connects closely with the mother’s
circulation to carry out functions, which the
fetus is unable to perform for itself during
intrauterine life.

3. DEVELOPMENT OF PLACENTA
• The small projections that appear on the
trophoblastic layer of the blastocyst proliferate
and branch from about 3 weeks after
fertilization, forming the chorionic villi.
• The villi become most profuse in the area where
the blood supply is richest, i.e. in the basal
decidua.

4. • This part of the trophoblast is known as
Chorion frondosum. It will eventually develop
into the placenta.
• The villi under the capsular decidua get less
nourishment and gradually atrophy and form the
chorion laeve or bald chorion.
• The villi erode the walls of maternal blood
vessels as they penetrate the decidua, opening
them up to form a lake of maternal blood in
which they float.

5. • The opened blood vessels are known as sinuses
and the area surrounding the villi as blood
spaces.
• Maternal blood circulates slowly in these vessels,
enabling the villi to absorb food and oxygen, and
to excrete waste.
• A few villi are attached more deeply to the
decidua and are called anchoring villi.
• Placental circulation is established by 17th day.

7. CIRCULATION THROUGH
PLACENTA
• Fetal blood that is low in oxygen is pumped
by the fetal heart towards the placenta
along their branches to the capillaries of the
villi.
• The blood returns to the fetus via umblical
vein after giving up carbon dioxide and
absorbing oxygen.

8. • Maternal blood is delivered to the placental
bed in the decidua by spiral arteries that
flow into the blood spaces surrounding the
villi.
• The blood enters the sinuses in a funnel
shaped stream similar to a fountain and as
it passes upwards, bathes the villus and
drains back into a branch of uterine vein.

11. MATURE PLACENTA
• The normal term placenta is a flattened
disk like mass with a circular or oval
outline.
• Average Volume = 500 ml (200-900ml)
• Average Weight = 500 g ( 200-800g)
• It often weighs approx. one sixth of baby’s
weight at term.

12. • Average diameter = 20cm
• Thickness = 2.5 cm
• The fetal surface of the placenta is smooth,
shiny and transparent. The underlying
chorion can be seen through it.
• The maternal surface is granular and
divided into 15-30 lobes (average 20) called
Cotyledons by a series of fissures termed as
sulci.

14. FUNCTIONS OF PLACENTA
• Respiration
• Nutrition
• Storage
• Excretion
• Protection

15. RESPIRATION
• The fetus obtains oxygen and excretes
carbon dioxide through the placenta.
• Oxygen from the mother’s hemoglobin
passes into fetal blood by simple diffusion
and similarly the fetus gives off the carbon
dioxide into the maternal blood.

16. NUTRITION
• All the nutrients are transported across the
placental membrane.
• Food from the maternal diet gets broken
down into simpler forms by the time it
reaches the placental site.
• The placenta selects those substances
required by the fetus.

17. STORAGE
• The placenta stores glucose, iron and
vitamins.
• Glucose stored in the form of Glycogen gets
reconverted to glucose when required.

18. EXCRETION
• Carbon dioxide is the major substance
excreted from the fetus.
• Other substances include bilirubin from
the breakdown of RBCs and small amounts
of urea and uric acid.

19. PROTECTION
• The placental membrane has a limited
barrier function.
• Certain antibodies, which the mother
possesses gets passed on to the fetus to
provide immunity for the baby for 3 months
after birth.

20. LIQUOR AMNII
• Amniotic fluid is also termed as liquor amnii, is
the fluid which distends the amniotic sac and
allows the growth and free movement of the
fetus.
• It equalizes the pressure and protects the fetus
from sudden vibrations.
• The fluid maintains constant temperature and
provides nutrients.

21. • In labor, it aids effacement of cervix and
dilation of os. As long as the membranes
remain intact, the amniotic fluid protects
the placenta and umblical cord from
pressure of uterine contractions.

22. CONSTITUENTS
• Amniotic fluid is a clear, pale straw colored fluid,
consisting of 99% water.
• The remaining 1% including food substances
and waste products.
• It contains fetal urine, respiratory tract
secretions and skin cells shed by the fetus, vernix
caseosa and lanugo.

23. SOURCE
• Amniotic fluid comes from both maternal
and fetal sources.
• Some fluid is exuded from maternal vessels
in the decidua and some from fetal vessels
in the placenta.
• Fetal urine also contributesto the volume
from the 10th week of gestation.

24. VOLUME
• At 38 weeks = 1 liter (1000ml)
• At term = 800 ml
• Polyhydramnios= Total amount more than
1500 ml
• Oligohydramnios = Total amount less than
300 ml

25. UMBLICAL CORD
• The umblical cord or funis extend from the
fetus to the placenta.
• It transmits the umblical blood vessels,
which are two arteries and one vein.
• These are enclosed by a gelatinous
substance known as wharton’s jelly.

27. • Average Length = 50 cm
• Short Cord = Less than 40 cm
• Certain cords are longer and with longer cords,
problems can arise. It may become wrapped
round the neck or body of the fetus and become
knotted.
• A true knot occurs when the fetus has passed
through a loop in the cord and a real knot is
created.

28. • False knotting of the cord occurs when the cord
appears to be knotted, but instead has kinking of
the blood vessels within the cord or accumulation
of lumps of Wharton’s Jelly on the side of the
cord.
• True knotting is most common in two situations:
– Small fetus, long cord and large amount of amniotic
fluid.
– Multiple gestation within a single amnion.

29. ABNORMALITIES OF PLACENTA
• Larger and heavier than normal placentas are
seen with excessively large fetus, fetal syphilis
and erythroblastosis .
• Smaller and lighter than normal placentas may
occur with general systemic diseases or local
uterine conditions, which causes
undernourishment of placenta and intrauterine
growth retardation

31. • The color of placental tissue is markedly lighter.
This is due to anemia or erythroblastosis.
• Excessive Infarct Formation: Infarction of
cotyledons due to maternal hypertension, pre
eclampsia or eclampsia.
• Edema of placenta: It is due to maternal heart
diseases, diabetes or nephritis.
• Syphilitic Placenta: Abnormally large, pale ,
yellow-grey placenta.

32. • Tumors are found in association with
prematurity and polyhydramnios. Perinatal
mortality and maternal hemorrhage are
both increased.
• Succenturiate Placenta/ Placenta
Succenturiate: One or more separate
accessory lobes in the membranes, a
variable distance away from the main
placental mass.

34. • Extrachorial Placenta: A placental anomaly
observed on the fetal surface as a thick white
ring, which gives the impression that the central
portion is somewhat depressed.
– Placenta Circumvallata/ Circumvallate Placenta: The
ring situated at a variable distance between the
margin and center of the placenta.
– Placenta Marginata/ Circummarginate Placenta: The
ring is located at the edge or margin of the placenta.

37. ANOMALIES OF UMBILICAL
CORD
• Battledore Placenta: A variation in which
the umbilical cord is inserted at the edge or
margin of the placenta.
• Velamentous Insertion: The cord is
inserted into the membranes at some
distance from the edge of the placenta.

39. • Short Cord: An absolute short cord is one ,
that is short in length.
• Long Cord: Long cord become looped
around the neck or body. It can also become
knotted and prolapsed in front of
presenting part.
• Cord Lopping
• Cord knotting.

40. DEVELOPMENT OF FETUS
FIRST TRIMESTER
• Zygote Formation
• Development of Chromosomes and genes
• Cellular Mass– Morula
• Morula becomes Blastocyst
• Embryonic period:
– The embryonic ectoderm
– The embryonic endoderm

41. During 3rd week:
• Neural Tube(rudiment of brain and spinal
cord)
• Notochord (rudiment of vertebrae)
• Coelemic spaces (rudiment of body
cavities)
• Primitive blood cells

42. 4th week
• At beginning heart starts to beat
• During 4th week; a longitudinal and
transverse folding of embryonic disk takes
place.
– Longitudinal folding: head fold and a tail fold
– Transverse folding: right and left transeverse
• By the end of 4th week; Embryo assumed
salamander look and has rudiments of ears,
legs, facial and neck structures

43. 5TH WEEK
• Rapid development of brain (head becomes
larger than rest of body)
• Development takes place from cephalic to
caudal, with development of legs a week behind
development of arms.
• The eyes begin development with lens, vesicles,
retina.

44. 6th WEEK
• Nose, mouth and palate begin to take form
and the eyelids become visible.
• Arms and legs undergo extensive
development
• By the end of 7th week; arms, legs are
formed with clearly defined fingers and
toes.

45. 7th Week
• During 7th week; neck region is established.
• Abdomen and urogenital development
begins
• By the end of 7th week; Embryo has
distinctive human characteristics

46. 12th week
• Intestines are fully into abdomen
• External Genitalia
• Anus has formed
• Facial Characteristics appears
• The fetus weighs about 0.5-1 ounce
• Swallowing begins and make respiratory
movements, urinate and move specific parts
of limbs
• Open and shut his/ her mouth.

47. SECOND ANDTHIRD
TRIMESTER
FOURTH MONTH(13-16 Weeks)
• Head growth slows, while ears move to a
higher elevation on the sides o f the head
and the chin becomes evident.
• Eyes remain closed and body growth
accelerates.
• Reflex responses and muscular activity
begins

48. • Gender is clearly distinguishable by 14th
week.
• Bone development takes place by 16th
week.
• The average crown-rump (top of head to
buttocks) length is 11.5cm
• Fetus weight between 99g- 113g

49. FIFTH MONTH (17-20 weeks)
• Rapid body growth continues; legs reach their
full length and toe nails develop.
• Eyelids remain fused.
• Fetus moves freely inside the uterus.
• Quickening begins at 18th week

50. • The fetus hiccups and the mother feels it as
a series of slight rhythmic jerks .
• By the end of 5th month, Vernic Caseosa
develops
• Fetal Heart Rate may be heard
• By the end of 20th weeks; Crown-rump
length is 16.5 cm
• Average weight is 341g

51. SIXTH MONTH (21-24 Weeks)
• Hair growth is prominent.
• The fetus is completely covered with languo;
Eyebrows, eyelashes and head hair are present.
• The head remains large compared to rest of
body.
• The skin is wrinkled, red.
• Makes motions of crying and sucking.

52. • The hands make fists.
• Brown fat which is a source of energy, heat
production and heat regulation in the newborn
forms.
• The average Crown-rump length is 20 cm
• Weight is 568 g.

53. SEVENTH MONTH (25-28 Weeks)
• The fetus continues to look old and wrinkled
though a little fat storage begins.
• By the end of the month; the body becomes
better proportioned because of weight gain.
• The eyes begin to open and shut.
• Crown –rump length= 22.5 cm
• Weight= 1023 g

54. EIGHT MONTH (29-32 WEEKS)
• Thick vernix caesosa covers entire fetus.
• Toe nails are present
• Fetus has control of Rhythmic breathing and
body temperature.
• Eyes are open.
• Crown-rump length= 27.5 cm
• Weight= 1.7 kg

55. NINTH MONTH (33-36 Weeks)
• Skin is smooth and is without wrinkles.
• Hair is larger
• Toenails has reached the ends
• Left testicle has usually descended into the
scrotum and plantar creases are visible.
• Crown-rump length= 31 cm
• Weight= 2.5 kg

56. SUMMARIZATION
Today we have discussed about:
• Development of Placenta
• Mature Placenta
• Liquor Amnii
• Abnormalities of Placenta
• Abnormalities of Umblical Cord
• Development of Fetus

57. RECAPTUALIZATION
• What is Amnotic cavity?
• What is Yolk sac?
• What is Placenta?
• What is umblical cord?
• What is circulation through placenta?
• Explain development of fetus.

58. BIBLIOGRAPHY
• Dutta D.C, Textbook of Obstetrics , 2004, Sixth
Edition, New Central Book Agency(P) Ltd. Pp
29-37.
• Jacob Annamma, A Comprehensive Textbook of
Midwifery & Gynecological Nursing, 4th Edition,
Jaypee Brothers Medical Publishers(P) Ltd;
2015. pp 75-82.