2. الرحيم الرمحن هللا بسم
َكَناَحْبُس ْاوُلاَقَل َمْلِع َالّالِإ آَن
ّنِإ آَنَتْمَّلع اَمَعْال َتْنَأ َكُميِل
ُميِكَحْال
العظيم اهلل صدق
سورةالبقرةأية32
Thursday, April 5, 2018 Dr. Soad Abd El salam Ramdan 2
3. 3
• Chairman of obstetrics &woman health
nursing department
• Pre. Vice dean for students &Education
Affairs
Thursday, April 5, 2018 Dr. Soad Abd El salam Ramdan
5. Thursday, April 5, 2018 Dr. Soad Abd El salam Ramdan 5
▪ Discuss concepts related to
fertilization (conception).
▪ Explore the process of
fertilization, implantation.
▪ Identify the process of fetal
development.
Objectives
6. FERTILIZATION
It is the process during which a male
gamete (sperm) unites with a female
gamete (oocyte) to form a single cell
(ZYGOTE).
7. Site
• Usually in the ampulla of the uterine
tube.
• Ampulla is the longest and widest part.
• Does not occur in the uterine cavity.
• Chemical signals from oocyte attract
the sperms.
9. Chromosomes in zygote
- Sex determination from the mature ovum carries 22 autosomes and one
x chromosome. while sperm carries 22 autosomes and either an x or y
chromosome. If the fertilizing sperm is carrying x chromosome the fetus
will be female(46xx), if it is carrying y chromosome the fetus will be
male(46xy).
- Half of its chromosomes come from the father and the other half
comes from the mother.
-Zygote is genetically unique. zygote contains 46 chromosomes
10. Sex of the Embryo
• Embryo's chromosomal
sex is determined at the
time of fertilization.
• Sex is determined by the
type of sperm
(X or Y) that fertilizes the
oocyte.
• So, it is the father whose
gamete decides the sex.
11. Gametogenesis
Cells are produced in two different methods:
mitosis and meiosis.
• Meiosis: is the process by which gametes are
produced
• Mitosis: is the process by which the cells
replicate to yield same genetic make up-
• Oogenesis: Cyclical
• Spermatogenesis: Continuous
Thursday, April 5, 2018 11Dr. Soad Abd El salam Ramdan
12. Oogenesis
• Occurs in females , is the creation of an ovum in the
ovary
• Oogenesis is regulated by hormones- Follicle
stimulating hormone (FSH) and LH.
• Only one oocyte is selected to continue meiosis each
month.
Thursday, April 5, 2018 12Dr. Soad Abd El salam Ramdan
15. Spermatogenesis
• Spermatogenesis is the process by which male
gametogonia develop into mature spermatozoa
• It occurs in the male testes and epididymis and takes
approximately 64 day.
• Sperm can live 72 hrs but more fertile for 48 hrs.
• The maturation of the male gamets, start at puberty
Thursday, April 5, 2018 15Dr. Soad Abd El salam Ramdan
18. Fertilization Process- Ovum
• The ovum is expelled from the mature follicle (graafian )
of the ovary and picked up by the fimbria.
• The ovum is surrounded by a ring of
mucopolysaccharide fluid (the zona pellucida) and outer
layer a circle of cells (the corona radiata)
• The lifespan of the oocyte is thought to be 6-24 hours.
• After fertilization the zygote undergoes cleavage
divisions whilst traveling through the uterine tube to the
uterus where it implants in the uterine wall.
Thursday, April 5, 2018 18Dr. Soad Abd El salam Ramdan
23. Fertilization
• Depends on key points
– Equal maturation of both ova and sperm
– Ability of sperm to reach ova
– Ability of sperm to penetrate the zona pellucida and
corona radiata
Thursday, April 5, 2018 23Dr. Soad Abd El salam Ramdan
24. Schema of ovulation, fertilization, and implantation
Thursday, April 5, 2018 24Dr. Soad Abd El salam Ramdan
25. Intra Uterine Life
• The development of the fetus (female and the male) is
initially the same until the 4th week.
• The zygote moves through the fallopian tube to the uterus
within 3-4 days.
• During this time (3-4) days the zygote continues to divide.
• Within 3 days a solid ball of cells, the Morula continues to
develop to form a central cavity or blastocyst
• Even at this early stage of development, cells begin to
differentiate in structure and function.
Thursday, April 5, 2018 25Dr. Soad Abd El salam Ramdan
26. Intra Uterine Life
• A fluid filled cavity in : morula which now becomes known as
blastocyst
• Blastocyst is the stage at which it embeds after 3rd or 4th free floating
in the uterus .
• about 8 days from ovulation. It attaches to the surface of
endometrium
• Endometrium after implantation is called deciduas
• Deciduas can be differentiated into 3 layes
• Decidus basalis under site of implantation.
• Decidus capsularis covering the ovum
decidua vera lining rest of uterine cavity
Thursday, April 5, 2018 26Dr. Soad Abd El salam Ramdan
28. Intra Uterine Life
• Small projection begin to appear over the
surface of blastocyst
• Called choronic villi the fluid filled cavity
pushes some of cells to one side and two
layers are formed :
• Outer cell mass (trophoblast) this is orgin
of placenta
• Inner cell mass become fetus(embroyblast )Thursday, April 5, 2018 28Dr. Soad Abd El salam Ramdan
29. After implanation 2 cavities appear in the inner
cell mass(embroyblast ) (ammiot sac
and yolk sac) in between them 3 main
layers which will form fetus developed :
Ectoderm , mesoderm , endoderm
30. Primary Germ Layers
Germ
Layer Body Portions Formed
Ectoderm Central nervous system (brain and spinal cord)
Peripheral nervous system
Skin, hair, and nails
Sebaceous glands
Sense organs
Mucous membranes of the anus, mouth, and nose
Tooth
Mammary glands
Mesoderm Supporting structures of the body (connective tissue, bones, cartilage, muscle,
ligaments, and tendons)
Upper portion of the urinary system (kidneys and ureters)
Reproductive system Heart Circulatory system Blood cells Lymph vessels
Entoderm Lining of pericardial, and peritoneal cavities
Lining of the gastrointestinal tract, respiratory tract, tonsils, parathyroid, thyroid
glands
Lower urinary system (bladder and urethra)
Thursday, April 5, 2018 30Dr. Soad Abd El salam Ramdan
31. Intra Uterine Life
• ectoderm mainly forms : skin and
nervous system.
• Mesoderm: forms bones and muscles
and heart & blood vessels
• Endoderm : forms mucous membranes
and glands
Thursday, April 5, 2018 31Dr. Soad Abd El salam Ramdan
32. Intra Uterine Life
• Implantation point is usually high of uterus (upper uterine
segment)
• If point of implantation is low in uterus growing placenta
may occlude cervix make birth of child difficult ( placenta
previa )
• 2/3 cases implanted in posterior surface of upper uterine
segment .
• 1/3 cases implanted in anterior surface of upper uterine
segment.
• After fertilization corpus luteum in the ovary continues to
function until the placenta formed (12 ws).
Thursday, April 5, 2018 32Dr. Soad Abd El salam Ramdan
33. Intra Uterine Life
The placenta :
• It is discoid in shape about 15-20 cm , 2.5 cm in thickness at
the center and weighting about 500 gm
• Has two surface .
• Fetal surface :- umbilical cord inserted at center of this
surface
• Maternal surface:- divided into 15-20 .cotyledons .
• The structure of the placenta is complete by the 12th week.
• At term, one-sixth the weight of the baby.
Thursday, April 5, 2018 33Dr. Soad Abd El salam Ramdan
34. Intra Uterine Life
Function of placenta :
• Exchange of gases (as lung ) respiration
• Execration (as urinary tract)
• Nutrition (as G.I.T)
• Secretion of hormones (as endocrine system)
• As (H.P.L). HGC
• Barrier action as protection
• As Storage
Thursday, April 5, 2018 34Dr. Soad Abd El salam Ramdan
35. Intra Uterine Life
Amniotic fluid:-
• One litre average if 2 litre or more called polyhydromenis if
less called Oligo hydromeris
• The volume reach to its peak at 38 w than slightly up to
term and rapidly decrase there after
• Is alkaline in reaction (PH.is 7 to 7.4)
•Composition 99 % water 1% solid as waste product Urea
enzymes , hormones lingua hairy Deed skin, verneix
casueasa
Thursday, April 5, 2018 35Dr. Soad Abd El salam Ramdan
36. Normal Amounts of Fluid
• 30 ml @ 10 weeks
• 350 ml @ 20 weeks
• 500 to 1000 ml after 20 weeks
• At Term 800-1200 ml
• Oligohydramnios=Too little <300ml pocket <1cm”
• Poly or Hydraminios=Too much >2L“pocket >8cm
• Genetic testing at 16 wks
Thursday, April 5, 2018 36Dr. Soad Abd El salam Ramdan
37. Intra Uterine Life
Function :
• Protection of fetus from external trauma.
• Facilitate the movement of the fetus.
• Execration of fetal urine
• Keeps fetal temperature constant
• Bag of water help to dilate cervix
• After rupture of membranes act as antiseptic
Thursday, April 5, 2018 37Dr. Soad Abd El salam Ramdan
38. Intra Uterine Life
• Umbilical cord :
• Development from mesoderm
• Length : 50 cm
• Insertion : centeral
• Content : 2 arteries & one vien surrounded by Wharton’s jelly
• Abnormality :
• Too long lead to prolapsed cord
• Coiling around the neck
• Too short lead to prolonged labour
or Premature separation of placenta
• Knots:
• True knote cause fetal death
Thursday, April 5, 2018 38Dr. Soad Abd El salam Ramdan
39. • Cephalocaudal (Brain before lungs)
• Proximodistal (Arms before fingers)
• Differentiation (Organs formed)
– All major organs are formed by day 17
to 56
Fetal Development Principles
Thursday, April 5, 2018 39Dr. Soad Abd El salam Ramdan
41. An early gestational sac prior to the appearance of a yolk sac
or other embryonic structure
Thursday, April 5, 2018 41Dr. Soad Abd El salam Ramdan
42. Terms Used to Denote Fetal Growth
Time PeriodName
From ovulation to fertilizationOvum
From fertilization to implantationZygote
From implantation to 5–8 weeksEmbryo
From 5–8 weeks until termFetus
Developing embryo or fetus and placental structures
throughout pregnancy
Conceptus
Thursday, April 5, 2018 42Dr. Soad Abd El salam Ramdan
43. – Viruses can cross the placenta and infect the fetus
– Some bacteria and protozoa first infect the placenta
then infect the fetus
– Drugs, caffeine, alcohol, nicotine, cocaine,
marijuana all cross the placenta to the fetus
Mechanisms of Placental
transportation:
Thursday, April 5, 2018 43Dr. Soad Abd El salam Ramdan
44. Placental Hormones
1. Human Chorionic Gonadotrophin (hCG): peak
at 50-70days then decrease detected in blood
serum by 8 to 10 days after conception.
– hCG maintain the function of ovarian corpus
luteum to ensure a continuous supply of
oestrogen and progesterone.
Thursday, April 5, 2018 44Dr. Soad Abd El salam Ramdan
45. 2. human Placental Lactogen (hPL):
• A growth hormone like-substance
• Stimulate maternal metabolism,
• Facilitate glucose transport across placental membrane,
• Stimulate breast development to prepare for lactation
3. Progesterone:
• Maintain the endometrial
• Decrease the contractility of uterus,
• Stimulate the breast alveoli development
• Assist in maternal metabolism
Placental Hormones
Thursday, April 5, 2018 45Dr. Soad Abd El salam Ramdan
46. 4. Estrogen
• At week 7 most of maternal oestrogen
from the placenta
• It stimulates uterine growth, cause
proliferation of breast glandular tissue,
• It stimulates myometrial contractility
Placental Hormones
Thursday, April 5, 2018 46Dr. Soad Abd El salam Ramdan
47. Placental function
Placental Function depends on maternal blood pressure:
1. Vasoconstriction _such that caused by hypertension-
diminish uterine blood flow
2. Decreased maternal blood pressure or cardiac output
diminish uterine blood flow- supine position
3. Excessive maternal exercise derives blood away from
uterus to muscles
4. Prolonged contraction and decreased interval between
them reduce blood flow to placenta
Thursday, April 5, 2018 47Dr. Soad Abd El salam Ramdan
48. Arrangement of the placental layers &
part
Thursday, April 5, 2018 48Dr. Soad Abd El salam Ramdan
50. Landmarks in Fetal Development
• 4 weeks-Fetal heart begins to beat
• 8 weeks-All organs are formed
• 8-12 weeks- Heartbeat heard with Doppler
• 16 weeks-Baby’s sex can be seen
• 20 weeks-Mother feels movement
• 24 weeks-Respiratory movements
• 28 weeks-can breathe in extra uterine life
Thursday, April 5, 2018 50Dr. Soad Abd El salam Ramdan
55. Embryo at Seven Weeks
Thursday, April 5, 2018 55Dr. Soad Abd El salam Ramdan
56. Week 8
The embryo is reactive to its environment inside the amniotic
sac where it swims and moves. Hands and feet can be
seen. At the end of week 8, the embryonic period is over and
the fetal stage begins.
Thursday, April 5, 2018 56Dr. Soad Abd El salam Ramdan
57. Embryo at Eight Weeks
Thursday, April 5, 2018 57Dr. Soad Abd El salam Ramdan
58. Fetus at 9 Weeks
Thursday, April 5, 2018 58Dr. Soad Abd El salam Ramdan
61. Fetus at 20 Weeks
Thursday, April 5, 2018 61Dr. Soad Abd El salam Ramdan
62. Hazards to Fetal Development
• Teratogens are……………………………
• Tissues are most vulnerable during the
embryonic stage when tissues are differentiating
into essential organs.
• Critical time: Day 16 to 56.
• Most women do not know they are even
pregnant (Preconceptual counseling)
Thursday, April 5, 2018 62Dr. Soad Abd El salam Ramdan
63. Week 20
• “Quickening” (when the mother can feel the
fetus moving) usually occurs around this time.
• Finger and toenails appear.
• Lanugo, a fine hair now covers the entire body.
• The fetus can hear and recognize the mother’s
voice.
• Sex organs are visible on ultrasound devices.
Thursday, April 5, 2018 63Dr. Soad Abd El salam Ramdan
66. Third Trimester
Week 24
A protective waxy substance called Vernix covers the skin. By birth,
most of the vernix will be gone but any that is left is quickly
absorbed. Fetus has a hand and startle reflex. Footprints and
fingerprints are forming. Fetus practices breathing by inhaling
amniotic fluid into its developing lungs.
Thursday, April 5, 2018 66Dr. Soad Abd El salam Ramdan