This document discusses fetal development from conception through the embryonic and fetal periods. It covers topics like formation of the three germ layers (endoderm, ectoderm, mesoderm), development of structures like the amnion, yolk sac and notochord, and fetal growth over the course of pregnancy. Key structures and organs derived from each germ layer are identified. Fetal circulation is described, as well as the development of major organ systems like the lungs, liver, kidneys and brain over the course of gestation. Factors influencing fetal growth and development are also summarized.

1. SHERIN SHANA
GOVT.COLLEGE OF NURSING
KOZHIKODE

5.  OVA :22+X
 SPERMATOZOA : 22+X
:22+Y

6. 22XX + 22X/22Y
44XX or 44XY

9.  Prevent implantation of the blastocyst at an
abnormal site
 Acts as a barrier that separates maternal
tissue from embryo and thus prevent the
immunological reaction

10.  At early stage of development ,the embryo
acquires the form of a three layered disc
called embryonic disc
 Three layers of embryonic disc
 Endoderm
 Ectoderm
Mesoderm

12.  Some cells of the inner cell mass differentiate
in to flattened cells , that come to line its free
surface .These constitute the endoderm.
 Remaining cells of the inner cell mass
become columnar.These cells form the
ectoderm.
 Space appears between the ectoderm and
trophoblast called amniotic cavity filled by
amniotic cavity or liquor amnii

13.  Flattened cells arising from the endoderm
spread and line the inside of the blastocystic
cavity .
 A cavity lined on all sides by cells of
endodermal origin ,is formed.This cavity is
called the primary yolk sac.
 Cells of the trophoblast give origin to a mass
of cells called the extra embryonic
mesoderm.

16.  Formation of Chorion and Amnion.
 Yolk sac become much smaller than before
and is now called secondary yolk sac.
 Cubical cells of the endoderm become
columnar.This area is called prochordal plate.
 Primitive streak.

18.  Cells that proliferate in the region of the
primitive streak pass sideways, pushing
themselves between the ectoderm and
endoderm.These cells form the intra
embryonic mesoderm.

19. DERIVATIVES OF ECTODERM
 LINING EPITHELIA
a) Skin
b) Mucous membrane of lips ,cheeks , gums,
part of the palate and nasal cavities etc
c) Lower part of the anal canal
d) Terminal part of the male urethra
e) Outer surface of the labia minora and whole
of labia majora

20. f) Anterior epithelium of cornea,
conjunctivitis, ciliary bodies
g) Outer layer of tympanic membrane
 GLANDS:
a) Exocrine : sweat gland, sebaceous
gland,parotid,mammary gland, lacrimal
gland
b) Endocrine:hypophysis cerebri,adrenal
medulla

21.  OTHER DERIVATIVES:
a) Hairs
b) Nails
c) Enamel of teeth
d) Lens of eye,musculature of iris,ciliary
muscles
e) Nervous system
f) Substance of cornea,sclera&choroid

22. Derivatives of endoderm
 LINING EPITHELIA:
a) Epithelium of part of mouth,part of the
palate,tongue,tonsil,pharynx,stomach,
b) Middle ear,inner layer of the tympanic membrane
c) Epithelium of the respiratory tract
d) Epithelium of the gall bladder,extra hepatic duct
system,pancreatic duct
e) Epithelium of the urinary bladder
f) Epithelium of the vagina

23.  GLANDS:
a) ENDOCRINE:Thyroid,parathyroid,thymus,islets of
langerhans
b) EXOCRINE:Liver,pancreas,glands in wall of GI tract
greater part of prostate

24. Derivatives of mesoderm:
 All connective tissues including loose areolar
tissue,superficial and deep fascia, ligaments,
tendons,dermis of the skin
 Specialized connective tissue like adipose
tissue ,reticular tissue,cartilage and bone
 Dentine of teeth
 All muscles
 Heart ,all blood vessels and lymphatics

25.  Kidneys,ureters,urethra,prostate
 Ovary,uterus,uterine tubes,vagina
 Testis ,epidydimis,ductus
deferens,ejaculatory duct
 Substance of ciliary body and iris
 Adrenal cortex
 Duramater,pia mater
 Substance of cornea,sclera,choroid

26.  Notochord is a midline structure ,that
develops in the region lying between the
cranial end of the primitive streak and the
caudal end of the prochordal plate.

27.  Cranial end of the primitive streak becomes
thickened .This thickened part of the streak is
called primitive knot.
 Depression appears in the centre of the
primitive knot called blastospore.
 Notochordal process

29.  Neural tube gives rise to the brain and spinal
cord.
 Neural tube is formed from the ectoderm
overlying the notochord and ,therefore
extends from the prochordal plate to the
primitive knot.
 Neural tube is soon divisible into:
 A cranial enlarged part that forms the brain
 Caudal tubular part that forms the spinal cord

30. After the development of the secondary yolk
sac
 Progressive increase in the size of the
embryonic disc

34.  Fetal period begin 8 weeks after fertilization
or 10 week after onset of last menses.
 Consist of growth and maturation of
structures that were formed during the
embryonic period.

35.  Uterus palpable above the symphysis pubis
 Fetal crown – rump length =6-7cm
 Centres of ossification appeared
 Fingers and toes become differentiated
 Skin and nails have developed.
 External genitalia beginning to show definitive
signs of male and female gender

36.  CRL =12cm
 Weight:110g
 Gender can be determined.

37.  Weight <300g
 Fetal movement start
 Skin has become less transparent
 Downy lanugos covers the entire body

38.  Weight=630g
 Skin characteristically wrinkled and fat
deposition begins
 Eyebrows and eyelashes are recognizable
 Lung development : bronchi and bronchioles
enlarge and alveolar duct develop

39.  CRL=25cm
 Weight=1100g
 Thin skin is red and covered with vernix
caseosa

40.  CRL =28cm
 Weight = 1800g
 Thick vernix caseosa covers the entire fetus
 Eyes are open
 Fetus has control body temperature

41.  CRL=39cm
 Weight=2500g
 Wrinkled appearance of the face has been lost

42.  Term
 CRL=36cm
 Weight =3400g

44. AMNIOTICFLUID:
 Ultra filtrate of maternal plasma
 By beginning of 2nd trimester it consists of largely
ECF
 After 20 weeks it consist of largely of fetal urine
 Amniotic fluid also contain
 Desquamated fetal cells
 Vernix
 Lanugo
 Various secreations

45.  Volume increases by 10ml/week at 8 week
 Increased up to 60 ml /week at 21 week
 Declines gradually back to a steady state by
33 week

46. Blood
 Fetal blood is form from inner cell mass
 Fetal haemoglobin termed as HbF(18-120g/dl)
 In utero RBC have shorter life span
 HEMOPOIESIS : demonstrable first in the yolk sac
 Next major site is the liver
 Finally bone marrow

47.  ERYTHROPOIESIS : Controlled by fetal
erythropoietin
 Fetal erythropoietin production influenced by
testosteron,estrogen,prostaglandin,thyroid hormone
and lipoprotien
 Site of erythropoietin production : fetal liver

48.  FETAL BLOOD VOLUME:
 Normal newborn =78ml/kg
 Blood contained in the placenta:45ml/kg
 Fetaoplacental blood volume at term=125ml/kg

49.  10th week : kidneys begin to function & fetus begins
to pass urine.
 18 week: 7-4 ml/day(urine)
 At term:27ml/hr(urine) or 650 ml/day

50.  3rd to 6 month : The liver is responsible for the
Formation of RBC
 Fetal cholestrol is from hepatic synthesis
 2nd trimester : Hepatic glycogen present in low
concentration

51.  Non functional before birth
 Forms from yolk sac
 Recognized prenatally by grossly enlarged
bowel during sonography

52.  Originate from a bud pharynx
bronchial tree
 Surfactant: Lipoprotien ,which reduces the
surface tension in the alveoli and assists gas
exchange
 At term: 100ml lung fluid
 3rd month : Some movement of the thorax
begin
 6th month : Diaphramatic movement begins

53.  Ectoderm overlying the notochord becomes
thickened to form the neural plate
 Neural plate neural groove neural
tube
 Neural tube: enlarged cranial part form brain
: narrow caudal part becomes
spinal cord

54. Cranial part of the neural tube
Prosencephalon Mesencephalon Rhombencephalon
Diencephalone
Telencephalon Myelencephalon
Metencephalone

55.  Fetus is covered with a white creamy
substance called vernix caseosa from 18
weeks onwards.
 At 20 week : fetus will be covered with fine
downy hair called lanugo.
 10th week : finger nail begin to form
 18th week : toe nail begin to form

57. From placenta single umbilical vein in umbilical
cord
Carry oxygenated blood
Goes to liver fetal umbilicus
Then it branches in to 2;one large branch and
one small branch
Enters the IVC and then RA of heart

58. 75% of blood from RA
Through foramen ovale
Goes to LA
LV
Coronary arteries and aorta
From aorta blood with 60% O2 saturation is pumped to
head, neck, superior extremities

59. 25% of blood in RA mixes with blood from SVC
Draining head ,neck and upper extremities
Enter RV
Pumped to pulmonary artery
This blood goes to collapsed lungs in small part
Drained back in to the left atria by pulmonary veins

60. Its large part goes to Descending aorta and to
abdominal aorta
Which supplies main body organs & legs

61. Major part of the blood from abdominal aorta
Goes to internal iliac arteries and 2 hypo gastric
arteries
These arteries run towards umbilicus
Enters the cord as 2 umbilical arteries

63. Closure of the umbilical arteries
Closure of the umbilical vein
Closure of the ductus arteriosus
Closure of the foramen ovale

64.  MATERNAL FACTORS:
 Prepregnancy weight
 Pregnancy weight gain
 Age
 Parity
 Nutritional
 Uteroplacental circulation

65.  FETAL BIOLOGICAL FACTORS:
 Fetal endocrine functions
 Intrauterine functions
 Congenital malformations
 PLACENTAL FACTORS:
 Placental hormones

66.  HERIDITARY CAUSES
 ENVIRONMENTAL CAUSES
1. Infections
2. Malnutrition
3. Antigenic reactions
4. Drugs and chemicals
5. Hormones
6. Physical factors