Unit 1.L3-Late Organogenetic & Fetal Periods of Human Embryo Flashcards
(115 cards)
1
Q
What is the size of 3 week embryo, 5 week embryo and 8 week embryo>
A
3: 3mm
5: 10mm
9: 22mm
2
Q
How does the structure change in week 5?
A
- Head grows rapidly & becomes large
- The facial prominences develop so much that they
contact the heart prominence. - The maxillary and mandibular prominences of the first arch are delineated.
- Cranially: A large stomodeum, brain folding & 4th ventricle are prominent
- Caudally: Neural tube primordium -> spinal cord
- The mesonephric ridge emerges as a site of the primordial kidney and urogenital system.
3
Q
What is inferior to all the pharyngeal arches?
A
pharynx
4
Q
What is the mesonephric ridge?
A
Primidal kidney
5
Q
What is a very key thing that happens in week 6
A
Embryo moves:
- Embryo show spontaneous movements in trunk & limbs.->Body arches & curls
6
Q
Embryo have what due early neural connections?
A
Reflex action to touch
7
Q
Early in 6th week: Regional differentiation of the upper & lower limbs:
A
– Elbows
– Large hand plates (starting to have digits)
– Digit primordia
– Foot plate (no digits)
- Auricular hillocks (primordial pinna),
- External acoustic meatus (external ear canal)
8
Q
What does the auricular hillocks form?
A
auricle of external ear
9
Q
When does umbilical herniation happen?
A
Late sixth week
10
Q
Lower limbs develop _ into the sixth
week
A
5 days late
11
Q
What happens in late sixth week?
A
- The eye become pigmented & prominent as
pigment retina is formed. - Head is large & bent over & touching the heart.
- The intestines enter the extraembryonic coelom in the proximal part of the umbilical cord, showing umbilical herniation to accommodate the large gut tube.
12
Q
What happens to accommodate large gut tube?
A
the intestines enter the extraembryonic coelom in the proximal part of the umbilical cord, showing umbilical herniation to accommodate the large gut tube.
13
Q
What happens in week 7?
A
14
Q
What signifying digits (fingers or toes) & wrist?
A
The limbs show notches between the digital rays on hand and foot plates, signifying digits (fingers or toes) & wrist.
15
Q
During 7th week, what is reduced?
A
Reduced communication between the primordial gut & umbilical vesicle.
16
Q
What happens to the bones during the 7th week
A
Bones of the upper limbs undergo endochondral ossification
17
Q
What accounts for the large size of the abdomen in week 7?
A
The liver prominence
18
Q
Week 7
What stops with the enlargement of liver?
A
Stops descent of heart and lungs
only liver periotum
19
Q
What happens in week 8
A
20
Q
What does the scalp vascular plexus form in week 8?
A
band across the head-> capillaries are formed
21
Q
What becomes more prominent in week eight?
A
A stubby nose and heavily pigmented eye (retina), with eye-lids become prominent.
22
Q
What rotates, separate and lengthen in week 8?
A
Upper limb rotate ventrally and fingers separate & lengthen, and the toes begin to separate
23
Q
What can virtually cut the embryo?
A
Magnetic Resonance Microscopy (MRM)
24
Q
What happens happen in week8?
A
25
What does the embryo develop and what does it begin in week 8?
* The embryo develops distinct human appearance.
* Purposeful limb movement begins-> limbs can touch each other
26
What occurs to the bones in week 8?
Femoral bone (thigh) ossification occurs and both hands and feet elongate and touch each other.
27
What is going on with the eyes in week 8?
The eye-lids fuse by epithelialization.
-- Urine formed->amniotic fluid caustic
* Closed because of urine
28
How to measure the length of embryo
29
Embryo 8-9 weeks:
On the brink of becoming a fetus.
30
What happens in ninth week to birth?
grow, grow, grow
31
What is the size of week 9 fetus?
38mm
32
From the 9th week to birth (38th week), the developing human is called a _
fetus
33
The fetal period is characterized by three features:
(1) Rapid growth of the body (increase in size and cell number), barring head (not growing as much)
(2) Tissue & organ differentiation (functional specialization of cells)
(3) Slow head-growth, while other organs and the body grows fast.
34
What is formed during the embryonic period?
Refinement of the organ primordia
35
How does growth occurs?
spurts at intermittent intervals
36
When does phenomenal weight gain in fetus occur?
Phenomenal weight gain in the Fetus during the 3rd trimester
37
What is viability?
is defined as the ability of fetuses to survive in the extrauterine environment
38
Most fetuses weighing _ at birth do not survive, therefore, are not called viable
<500g
39
What are immature infants?
* Full-term, low-birth-weight infants resulting from **I**ntra**U**terine **G**rowth **R**estriction **(IUGR)**
* With expert postnatal care, some fetuses do survive; called extremely low-birth- weight infants, or immature infants at full-term.
| Not premature
40
What are preterm infants
Fetuses (750 -1500 g) that usually **survive**, but complications may occur; such as **BPD (bronchopulmonary dysplasia) or RDS (respiratory distress syndrome)**, and are called **preterm infants**
## Footnote
* BPD: alvoli do not align therefore cannot consume as much O2
* RDS: comp. lung fxn, growth not good
41
_ births/year in US, some with severe morbidity and mortality.
500,000 preterm infants
42
What is used to have reduced acute and long-term morbidity
The use of antenatal steroids and postnatal administration of endotracheal surfactant
43
Prematurity remains the most common causes
morbidity and perinatal death.
44
Clinical gestation: has 3 periods (3-trimesters = ~9-months), each lasting 3 months
(1) At **First trimester**: Major organ systems continues to develop.
(2) At **second trimester**: The fetus grows & anatomical detail are visualized by ultrasonography.
* Major birth defects are detected by high-resolution real-time ultrasonography or MRM.
(3) At **third trimester** (after 6 months): The fetus may survive if born prematurely
45
What happens in third trimester?
-- At 35 weeks the fetus weighs 2,500 g (5.5 lb) and is a measure of fetal maturity.
-- At 35 weeks, fetuses usually survive if **born prematurely**
--Normal gestation period is 40 weeks (1st day of the woman's last menstrual period)
46
What is the clinical term (due date)
Estimated Date of Confinement (EDC)
47
Actual in utero growth is what?
2 weeks less (fertilization to birth=38 weeks)
48
What is the Nägele's rule?
49
What determines the fetus the size, age and date of delievery of 9 week old fetus?
Ultrasound measurements of the Crown−Rump Length (CRL) of the fetus determines size, age & date of delivery
50
What is the CRL of 9 week old fetus?
4.2 cm
51
9-Week-old Fetus: Ex vivo Structures
Fetus with Chorionic Sac removed:
-- cartilaginous ribs
-- large head
-- intestinal growth is fast & descend in the umbilical cord
-- the face is broad
-- eyes are widely separated, eye-lids fused
-- ears are low set
52
What happens from 9 to 12 weeks
53
What happens to the intestines during 9th to 12th week
The intestines go back in the abdomen & are not in the umbilical cord
54
What is establised 9-12th week
**Primary Ossification Centers** are established (Cranium (skull) & Long Bones)
55
What is fully grown at 9 to 12 week?
Upper limbs are fully grown compared to the lower limbs
56
What develops and visible in 12th week
External male & female Genitalia develop & are visible by 12 weeks, but remain small
57
What is 12 week old fetal physiology?
58
At 9 weeks what happens to the liver?
At 9-weeks, Liver initiates erythropoiesis (making of RBCs: Red blood cells)
59
At 12-weeks, erythropoiesis switches to _
Spleen
60
What happens in 9th-12th with urine?
Urine formation begins & is discharged via urethra into the amniotic fluid in the amniotic cavity
61
What happens to swallowing amniotic fluid?
* the fetus reabsorbs amniotic fluid in the gut after swallowing it bc so salty
* fetal waste products goes into maternal circulation via the placenta
62
12-Week Fetus Imaging Modalities:
Look for Cranio-facial defects
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# 16th week
* When is the fetal growth the most?
* What is smaller?
* What contines to lengthen?
* Fetal growth is greatest (9-16th week); 25-fold by weight
* While the growth is very rapid the head is
* smaller.
* Lower limbs continue to lengthen.
64
What happens to the limbs in 16 week fetus?
* Limb movements are well-coordinated, but too slight to be felt by the mother. (because of muscle and leran how to use them)
* Limb movements are visible during ultrasonographic examination.
65
What is the size of 12 week old fetus, 38 week?
* 2.5 inch
* 20 inch
66
What is happening 16th week?
67
What is the fetal development of 17 week fetus
68
Relationship between age and egg quality
Deterioration after age 30
69
What happens during 17th to 20th week (5 months)
70
T/f: during 17th - 20th week of fetus is growing super fast
FALSE: super slow
71
What happens to featal movements during 17th to 20th week?
Fetal movements quicken; felt by the mother very often.
72
Eyebrows and head hair are well-developed & properly visible When
20 week of age
73
What happens to fat during 17th to 20th week?
Brown fat (root of the neck) for heat production at birth.
74
What is formed during 17th to 20th week
Fetal uterus is formed and canalization of the vagina begins
75
* What is visible for female fetus at 17 to 20 weeks?
* What happens in male fetuses?
* Primordial ovarian follicles containing oogonia are visible.
* In males, the testes descends, but remains in the posterior abdominal wall.
76
By 20th week what happens to the skin?
the skin has greasy /waxy white substance, which has a cheese-like consistency, called the “vernix caseosa”
77
* What does the vernix do?
* What is made up of?
* The vernix protects the fetal skin from abrasions, chapping, and hardening as it is exposed to the salty amniotic fluid.
* Vernix is made of dead epidermal cells& fatty sebaceous exudate from fetal sebaceous glands.
78
What does the fetus have for the vernix to stick?
Fetus has fine downy hair(called lanugo), for vernix to stick.
79
What occurs during 21-25th week?
80
What happens to weight and what is detected in 21-25 weeks
Substantial weight gain; body proportions are well defined and fingernails are detected
81
Wrinkled & translucent skin; pink to red because of blood
capillaries develop by what?
24 weeks
82
What happens to eyes at 21-25 weeks
* Rapid eye movements/blink−startle responses.
83
What happens to lungs at 21-25 weeks
Lungs begin maturation: the secretory epithelial cells (type II pneumocytes) in the lung alveoli secrete surfactants
84
What is surfactant?
Surfactants (lipoproteins) maintain patency ( i.e. keeps the lung open for air breathing and does not allow its membranes to stick) of the developing alveoli of the lung
85
* A 25 week old fetus bone prematurely may survive in NICU if what?
* What is there a risk for?
* if surfactant therapy is given endotracheally; a standard of care in the NICU.
* Risk for neurodevelopmental disability remains high.
* Risk of BPD (bronchopulmonary dysplasia) is high
86
What happens during 26-29 weeks?
87
What happens to Fetal Lung Development and Maturation: Week 26 onwards
88
What happens at 30-38th week ?
89
World Health Organization (WHO) Statistics on Premature Births
90
Complications in Pregnancy: Maternal Mortality
91
# Last trimester
At full term, CRL = _ mm and Weight = _ g ( _ lb.)
At full term, CRL = 360 mm and Weight = 3400 g (7.5 lb.)
92
What is happens in the last trimester?
93
What are low birth weight causes?
94
Major causes of IUGR (Intrauterine Growth Restriction):
95
* What is preterm neonates
* What is postmaturity syndrome?
* What are signs of fetal dysmaturity?
96
What are some causes in low birth weight and high birth weight?
97
What are other factors that influence fetal growth?
98
Assessment of fetal status (26 weeks to 4 weeks after birth) is done by what?
perinatologists
99
Methods employed for assessment:
- (1) Diagnostic Ultrasonography
-- (2) Diagnostic Amniocentesis
-- (3) Chorionic Villus Sampling (CVS)
100
What is dianostic ultrasonography?
101
What is diagnostic amniocentesis?
102
What is the Diagnostic Value of Amniocentesis
103
What is Chorionic Villus Sampling (CVS)
104
What is congential malformations (birth defects)
developmental anomalies or disorders that show anatomical/strucural or mental abnormality at birth
105
What are is the leading casue of infact mortality?
birth defects
106
What are some birth defects (5)
107
What is Teratology
Principles of [Embryology + Pathology + Toxicology] to understand & classify developmental defects of malformed embryos and fetuses.
108
What is Teratology (concept)"
Certain stages of embryonic development are more sensitive to “factors” that disrupt normal growth.
109
Effect of Teratogens depend on:
- Critical periods of development
-- Dose of the drug or chemical
-- Genetic background of the embryo
110
What is a earlier medical belief?
Baby’s are protected in the womb by sterile environment. This concept changed in 1941: Rubella Virus infection in pregnant mothers caused German measles, which lead to “congenital rubella syndrome”.
111
What is Congenital Rubella Syndrome
112
Congenital Rubella Syndrome: Eye anomalies:
113
What is the background of thalidomide?
114
What is spina bifida cystica?
115
What are the Classification of the causes of birth defects
