Foetal Period, Placenta and Foetal Membrane Flashcards
1
Q
An embryo changing into a foetus is a gradual process. Why is the name change meaningful?
A
Signifies that the primordia of all the major systems have now been formed.
2
Q
What happen during feotal period development
A
Rapid body growth
Differentiation of tissues, organs and systems
3
Q
It is important to note that periods of normal continuous growth alternates with what?
A
Prolonged intervals of absent growth
4
Q
Under foetal age estimation. Ultrasound machines are able to measure what?
A
CRL (Crown-Rump length)
5
Q
CRL assists with what?
A
Size determination and probable age in order to predict expected date of delivery
6
Q
In clinical practice gestational age is timed from?
A
The onset of the LNMP (last normal menstrual periods)
7
Q
In Embryology the LNMP is?
A
Redundant since gestation may not begin until the oocyte is fertilized-occurs around the middle of a menstrual period
8
Q
Intrauterine period is divided into?
A
Weeks, months and days
9
Q
The gestational period is divided into three trimester, each lasting how many months?
A
3 months
10
Q
The gestational period is divided into three trimester, each lasting 3 months, name those trimesters and describe them?
A
1-3 months: at the of the first trimester major systems gave developed
4-6 months: foetus grows sufficiently in size for anatomical features to be recognized on ultrasoun,d. Birth defects can be detected using Hi-Res Real Time Ultrasonography.
7-9 months: foetuses born at the beginning of this period may survive if born prematurely
11
Q
Organ systems are present by the 8th week, and all of them are fully functional.
True or False
A
False
All organ systems are present by 8th week, not all of them are fully functional
12
Q
The circulation system become complete when?
A
3rd month
13
Q
Heart and blood vessels are able to circulate blood when?
A
4th week
14
Q
Is it true or false.
Some organs only finish maturing after birth. Motivate your answer
A
True, example reproductive system. Slowest maturing organ is the brain as the cerebrum abs cerebellum are quite immature at birth
15
Q
What is happening during week 9 (4 marks)
A
- Face is broad, eye widely separated, ears are low and eyelids are fused.
- Legs are short and thighs are relatively small
- External genitalia of males and females appears similar
- Liver is major site for the erythropoiesis (Red blood cell formation)
16
Q
What is happening in week 10-11. (1 mark)
A
Intestinal cord are returned back to the abdomen by the 11th week.
17
Q
What’s is happening during week 12 (3 marks)
A
1.Primary ossificatiom centre’s appears in skeleton, UL has reached relatively final length and LL is still slightly shorter
2.Mature form of external genitalia reached
3.Erythropoeisis activity decreased in liver, has begun in spleen
18
Q
Name the specific thing that happen during week 9-12
A
Urine formation begins and urine is discharged via urethra into amniotic fluid.
19
Q
Name four things happening during 14 week (4 marks)
A
- Limb movement are co-ordinated, too small to be felt by the mother but can be seen on ultrasound
- Ossification of skeleton of foetus is active, developing bones visible
- Slow eye movement
- External genitalia can be recognised
20
Q
What is happening in week 16 (2 marks)
A
1.Ovaries contain primary ovarian follicles
2.Eyes face anteriorly and not anterolaterally, external ears are close to definitive position
21
Q
What happening in week 17- (3 marks)?
A
- Foetal movements “quickenings” are felt by the mother
- Skin starts to be covered with a greasy material - vernix caseosa
- Foetus covered with a downy fine hair-lanugo which helps the vernix caseosa adhere to the skin
22
Q
What is happening during 18 (1 mark)
A
Foetal uterus forms and canalization of vagina begins
23
Q
What is happening during week 20 (2 marks)
A
- Eyebrows and head hair is visible
- Testes has begun to descend but are still located on the posterior abdominal wall - as are ovaries
24
Q
What is vernix caseosa
A
The mix of dead epithelial cells and fatty substances from foetal sebaceous glands, protects skin from abrasions, chapping and hardening as a result of exposure to amniotic fluid.
25
What is happening during week 21 (2 marks) and 21- ( 1 mark)
21- rapid ete movements
Secretory epithelial cells begin to secrete surfactant
(21-) - Skin is wrinkled and more translucent, pink red since blood in capillaare still visible
26
What is happening during week 24 (1 mark)
Fingernails present
27
What will happen to a foetus born during week Twenty-first to Twenty-fifth weeks?
Foetuses born during this period may survive if given intensive care, but due to poor developed respiratory system they may die, also has a high risk of having a neurodevelopment disorder.
28
What happen during week 26 ( 1 mark), and week (26-) (2 marks)
Week 26 - eyelids open
Week (26-) - laugh and head hair well developed
Toenails visible
29
What will happen between week -28 (2 marks), what will happen during week 28 (1 mark)
-28 - lung and pulmonary vasculature developed sufficiently for gas exchange
Central nervous system matured enough to direct rhythmic breathing movements and control temp
28 - spleen stops being site of ethropoiesis, bone marrow becomes major site for erythropoiesis
30
What will happen to a foetus born between Twenty-Sixth to Twenty-Eighth weeks?
Foetus born in this period can survive if given intensive care
31
What happen during week 30 (1 mark) and 30- (2 marks)
Weel 30- pupillary reflex develops
Week (30-) - limbs have a chubby appearance
Skin is pink and smooth
32
True or False
Foetuses 32 weeks and older usually survive if born prematurely.
True
33
What is happening on week 35 (2 marks)
CNS mature enough to carry out integrative function
Have a firm grasp
34
What happen during week 36 (1 mark)
Circumferences of head and abdomen are equal
35
What happen during week 37 (1 mark)
Foot length is slightly larger than femoral length
36
What happen during week 38 ( 2 marks)
Prominent thorax, breast protrudes in both sexes
Testes present in scrotum
37
Expected Delivery?
266 days/38 weeks after fertilization
280 days/ 40 weeks after LNMP
38
List factors influencing Foetul Growth
1. Antibiotics
2. Cigarettes smoking
3. Terotogens
4. Alcohol and illicit drugs
5. Retinoic acid
39
True or false
Factors that are present in the third trimester, such as maternal malnutrition produce underweight infatnts
True
40
Factors affecting foetal growth may tend to produce infants with?
IUGR (intra-uterine growth restriction)
SGA (Small-for-Gestational Age)
41
Teratogens are classified into four types name those types
1. Physical agents
2. Metabolic conditions
3. Infection
4. Drug and chemicals
42
What are teratogens
Teratogens are substances hat may produce functional or physical defects in the human embryo or foetus after a pregnant female is exposed to the substance.
43
Exposure to teratogens affect the embryo and foetus in several ways depending on duration of exposure only.
True or false
False
Exposure to teratogens affect the embryo and foetus in several ways depending on duration of exposure amount of teratogenic substances and stage of development of the foetus
44
On average birth weight of infants whose mothers smoke 300 g less than normal, this increases the rate if prenatal morbidity
True or false
False because is 200 g
45
Cigarette smoking also causes
Cleft lip and palate
Gastroschisis (an opening in the abdominal wall)
Limb reduction
46
Name the teratogens agents from smoking and when does it affect pregnancy
Nicotine
Most adverse effects of nicotine are felt in the third trimester
47
What causes holoprosencephaly
Ingestion of 90 ml of alcohol per day for the four weeks of pregnancy
48
Exposure to alcohol and illicit drugs what will it cause later in pregnancy
Lead to more subtle defects due to the physiological maturation of the brain
49
Foetal alcohol syndrome, resulting from an alcohol intake will cause:
Poor post-natal growth rate
Mental retardation
Heart defects
Hypoplasia (underdevelopment) of facial structures.
Holoprosencephaly
50
What is tetracycline
Tetracycline is an antibiotic used to treat infections
51
Used of tetracycline during 2nd and 3rd trimester can result in:
Discoloration of infant milk teeth
Bone growth
Hypoplasia (underdevelopment) and staining of enamel
52
What is isoretinoin (Accutane)
Isoretinoin is a drug used to treat severe acne that has not responded to other treatment. This is a derivative of retinoic acid (vitamin A), which is a teratogen when taken orally.
53
Taking retinoic acid/isoretinoin produces a wide variety of defects that mainly affects derivatives of what?
Cranial Neural crest cells
54
Name under defects under retinoic acid
External ear malformation
Cleft palates
Undersized jaws (microagnathia)
Hydrocephaly (build ip of fluid inside the skull leading to brain swelling)
Microcephaly
55
List procedures for assessing foetal status
Ultrasonography
Diagnostic Amniocentesis
Chorionic villus sampling
Non-invasive pre-natal diagnosis
Percutaneous umbilical cord blood sampling
56
What is Ultrasonography
Primary imaging modality in evaluation of fetuses.
57
What can be viewed under Ultrasonography
Chorionic sac and it's content can be visualized
Placental and foetal sizes are monitored and can detect multiple births
Accurate measurements in terms of biparietal diameter of the foetal cranium can be obatined
58
What is diagnostic amniocentesis
An invasive prenatal diagnostic technique
59
What is done during diagnostic amniocentesis
Performed from 15 weeks
Amniotic fluid is sampled by inserting a needle through the maternal anterior abdominal and uterine wall into the Amniotic cavity
60
What's disorder can the diagnostic amniocentesis detects
Detect genetics disorder such as trisomy 21 (Down syndrome)
61
True or false
Diagnostic amniocentesis has a small risk (0.5 - 1.0 %) to foetus
62
What is Chorionic villus sampling
An invasive diagnostic technique
63
How is chorionic villus sampling done?
Biospy of trophoblastic tissue is obtained by inserting a needle through the maternal anterior abdominal and uterine walls into the uterine cavity.
64
The chorionic villus sampling what is user for
Used for assessing a foetus at risk- foetus karyotype can be obtained which allows a diagnosis to happen weeks in advance
65
When is chorionic villus sampling performed?
Performed from 10-12 weeks, risk to the foetus is 0.5-1.0%.
66
Example or non-invasive prenatal diagnosis
Non-invasive screening of trisomy 21 using a foetal cells in maternal blood and detection of cell-free foetal DNA and RNA
67
How is percutaneous umbilical cord blood sampling done
Foetal blood sample is obtained from the umbilical vein for diagnosis of several foetal conditions- aneuploidy, foetal infection, foetal anemia
68
When is percutaneous umbilical cord blood sampling
This is usually performed after week 17 the risk to the foetus is 1.3 %
69
Percutaneous umbilical cord sampling also permits what?
This procedure also permit tratubg the foetus directly, including the transfusion of packed red blood cells for management of foetal anemia resulting from isoimmunization
70
Role of the placenta
Nutrients and oxygen pass through the placenta from maternal to foetal blood
71
What is conceptus
Embryo + chorion + amnion
72
What is the decidua
Endometrium of a pregnant female
73
Name and describe the functional layers separating from the uterus at parturition
1. Decidua basalis- deep to the conceptus maternal part
2. Decidua capsula- superficial part overlying conceptus
3. Decidua parietalis- remaining part
74
Maternal part composed of?
Decidua basali and foetal components
75
Foetal part compose of?
Chorion frondosum and interbillous space
76
Development of the placenta. When is started and how.
A complex vascular network is established in the placenta by end kf week 4 facilitating the exchange of gas, nutrients and metabolic waste between maternal and embryo systems.
77
How is chorion laeve formed
Chorionic villi cover the entire chorionic sac until the beginning of week 8, and the chorionic dac grows the villi that is in contact with the decidua capsularis becomes compressed which reduces blood supply. These villi then degenerate to prodece a smooth chorion. Known as chorion laeve
78
How is the chorion frondosum formed
The degeneration of this villi causes an increases in the villi that is in contact with the decidua basalis which form a bushy area of the chorionic sac, known as chorionic frondosum
79
Foetal part is attached to maternal part of the placenta by?
Cytotrophoblastic shell
80
Endometrial arteries enter the gaps of this shell to enter what?
Intervillous space
81
What enlarges the intervillous space
As the chorionic villi invade the decidua basalis the decidua tissue is eroded to enlarge the intervellious space
82
What produces the placenta septa
The erosion produces wedge shaped area of decidua known as placenta septa
83
What does the placenta septa does
The placenta septa divide the foetal part of the placenta into cotyledons
84
What does the cotyledon have
Has two or more villi and several branch villi
85
By the end of which month is the decidua basalis is almost entirely replaced by cotyledons
4th month
86
What allows only the maternal plasma to enter the intervillous spaces
Initially trophoblast invades spiral arteries and creates plugs within the arteries which allows only maternal plasma to enter the intervillous spaces
87
By which week is the plugs breaks down maternal blood begins to flow into these spaces
Week 14
88
When the intervillous spaces are divided by the septa what does the septa don't do
The septa don't seal off the cotyledonsz therefore it is an open communication between the compartment
89
Amniochorionic membrane is also the fusion of?
Amniotic sac and chorion laeve, this what ruptures at the start of labour and releases amniotic fluid
90
Where does the branch villi emerges from and what its provide
Emerge from stem villi
Provide an increase surface area for exchange of materials across the plasma membrane
91
Explain in details what is happening during placenta circulation in foetal part (10 marks)
1. Deoxygenated foetal blood passes from umbilical arteries into the placenta
2. At the site of the umbilical cord these arteries divide into chorionic arteries which enter chorionic
villi
3. Blood vessels then form an extensive arterio-capillary-venous system within the chorionic villi
which brings the foetal blood extremely close to the placental membrane and in turn the maternal
blood
4. Oxygenated foetal blood in the foetal capillaries then pass into veins which converge at the site of
the umbilical cord
5. These veins then form the umbilical vein which carries the oxygenated blood to the foetus
92
Maternal blood that enters the intervillous space is temporarily outside the maternal circulatory
system. True or false
True
93
Placenta circulation based on Maternal part
1. Maternal blood enters the intervillous space via endometrial spiral arteries
2. Blood returns via endometrial veins to the maternal circulation.
94
What is parturition
Process during which the foetus, placenta, and foetal membranes are expelled from the mothers reproductive tract
95
What happen at labour
Sequence of involuntary uterine contractions resulting in dilation of cervix and expulsion of foetus and placenta
96
Name 3 stages of labour
Labour stage one- Dilation
Labour stage two- expulsion
Labour stage three- Placental
97
What happen during stage one of labour Dilation
Begins with progressive dilation of cervix and ends when cervix is fully
dilated.
• Regular painful contractions occurring less than ten minutes apart.
• Can last for 12hrs if it is the first pregnancy and about 7hrs if the mother
has had a baby before.
98
What happen during stage two of labour expulsion
Begins with fully dilated cervix, ends with delivery of foetus
• Foetus descends through cervix and vagina
• When the baby is outside the mothers body it is now termed neonate
• Can last up to 50 mins
99
What happen during the third stage of labour
Placental
• Begins when neonate is born, ends with expulsion of placenta and
membranes.
• Can last approximately 15mins
• A retained placenta is one that is not expelled within 60mins of delivery,
and can lead to severe infection and blood loss.
100
What does the amnion do?
The amnion forms a fluid-filled membranous amniotic sac which surrounds the foetus.
• As the amnion enlarges it completely obliterates the chorionic cavity and also forms the
epithelial lining of the umbilical cord.
101
The amniotic fluid, present in the amniotic sac, has the functions. List 5 functions
1. Barrier to infection
2. Normal foetal lung development
3. Prevents adherence of amnion to foetus
4. Cushions foetus against injuries
5. Assists in maintaining homeostasis
102
What does the umbilical vesicle turns to?
By the 10th week the umbilical vesicle has shrunk to a pear-shaped remnant
and is connected to the midgut bu a narrow omphaloenteric duct.
• By the 20th week the umbilical vesicle is small and thereafter not quite
visible
103
Significance of umbilical vesicle
Transfer of nutrients to the embryo in 2nd and 3rd weeks.
- Blood cell development, in wall of umbilical vesicle until the
hematopoietic activity in the liver in week 6.
- Incorporated into the embryo as a primordial cyst and assist in forming
the bronchi, lungs, trachea and alimentary canal.
104
Umbilical cord have?
Has two arteries, one large vein and is surrounded by a mucoid connective tissue (Whartons
Jelly
105
Development of the umbilical cord
End of the 3rd week the embryo is attached to the placenta via the connecting stalk.
• By the end of the 5th week there is a primitive umbilical ring which contains the connecting
stalk, allantois, two umbilical arteries and one umbilical vein.
• By the 10th week the gastrointestinal tract protrudes through the umbilical ring as a herniation,
forming the umbilical cord.
106
Explanation of the attachment of the umbilical cord
Attachment of umbilical cord to the placenta is usually near the centre of the foetal surface.
• Attachment of the cord to the foetal membrane is termed a ‘velamentous insertion’.
107
Are the following statements true of false.
1. Umbilical cords are usually 1-2cm in length, longer cords have a tendency to prolapse and
coil around the foetus.
2. Prompt recognition of a prolapsed cord is important since it can lead to foetal hypoxia or
anoxia.
3. If oxygen deficiency lasts for longer than 5 minutes the neonates’ brain can be damaged.
1. False, 1-2 cm in diameter
2. True
3. True
108
The loop of the bowel retract from the ? And when?
The loops of the bowel retract from the herniation around the 3rd month and the structures of
the cord remain.
109
How does the Allantois appears
Appears as a diverticulum (small out-pocketing) from the
caudal wall of the umbilical vesicle (a.k.a yolk sac), which then
extends into the connecting stalk
110
What does the allantois blood vessels do
Blood vessels present here persist as the umbilical arteries and
umbilical vein
111
Explain everything you know about urachus.
The proximal part of the allantoic diverticulum persists as a
stalk – URACHUS, which then extends from the bladder to the
umbilical region
- The urachus is present in adults as the median umbilical
ligament
