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Embryology: Summer Semester > Unit 1.L3-Late Organogenetic & Fetal Periods of Human Embryo > Flashcards

Unit 1.L3-Late Organogenetic & Fetal Periods of Human Embryo Flashcards

1
Q

What is the size of 3 week embryo, 5 week embryo and 8 week embryo>

A

3: 3mm
5: 10mm
9: 22mm

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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.
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3
Q

What is inferior to all the pharyngeal arches?

A

pharynx

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4
Q

What is the mesonephric ridge?

A

Primidal kidney

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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
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6
Q

Embryo have what due early neural connections?

A

Reflex action to touch

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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)
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8
Q

What does the auricular hillocks form?

A

auricle of external ear

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9
Q

When does umbilical herniation happen?

A

Late sixth week

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10
Q

Lower limbs develop _ into the sixth
week

A

5 days late

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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.
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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.

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13
Q

What happens in week 7?

A
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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.

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15
Q

During 7th week, what is reduced?

A

Reduced communication between the primordial gut & umbilical vesicle.

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16
Q

What happens to the bones during the 7th week

A

Bones of the upper limbs undergo endochondral ossification

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17
Q

What accounts for the large size of the abdomen in week 7?

A

The liver prominence

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18
Q

Week 7

What stops with the enlargement of liver?

A

Stops descent of heart and lungs

only liver periotum

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19
Q

What happens in week 8

A
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20
Q

What does the scalp vascular plexus form in week 8?

A

band across the head-> capillaries are formed

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21
Q

What becomes more prominent in week eight?

A

A stubby nose and heavily pigmented eye (retina), with eye-lids become prominent.

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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

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23
Q

What can virtually cut the embryo?

A

Magnetic Resonance Microscopy (MRM)

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24
Q

What happens happen in week8?

A
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25
Q

What does the embryo develop and what does it begin in week 8?

A
  • The embryo develops distinct human appearance.
  • Purposeful limb movement begins-> limbs can touch each other
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26
Q

What occurs to the bones in week 8?

A

Femoral bone (thigh) ossification occurs and both hands and feet elongate and touch each other.

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27
Q

What is going on with the eyes in week 8?

A

The eye-lids fuse by epithelialization.

– Urine formed->amniotic fluid caustic
* Closed because of urine

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28
Q

How to measure the length of embryo

A
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29
Q

Embryo 8-9 weeks:

A

On the brink of becoming a fetus.

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30
Q

What happens in ninth week to birth?

A

grow, grow, grow

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31
Q

What is the size of week 9 fetus?

A

38mm

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32
Q

From the 9th week to birth (38th week), the developing human is called a _

A

fetus

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33
Q

The fetal period is characterized by three features:

A

(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.

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34
Q

What is formed during the embryonic period?

A

Refinement of the organ primordia

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35
Q

How does growth occurs?

A

spurts at intermittent intervals

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36
Q

When does phenomenal weight gain in fetus occur?

A

Phenomenal weight gain in the Fetus during the 3rd trimester

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37
Q

What is viability?

A

is defined as the ability of fetuses to survive in the extrauterine environment

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38
Q

Most fetuses weighing _ at birth do not survive, therefore, are not called viable

A

<500g

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39
Q

What are immature infants?

A
  • Full-term, low-birth-weight infants resulting from IntraUterine Growth Restriction (IUGR)
  • With expert postnatal care, some fetuses do survive; called extremely low-birth- weight infants, or immature infants at full-term.

Not premature

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40
Q

What are preterm infants

A

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

  • BPD: alvoli do not align therefore cannot consume as much O2
  • RDS: comp. lung fxn, growth not good
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41
Q

_ births/year in US, some with severe morbidity and mortality.

A

500,000 preterm infants

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42
Q

What is used to have reduced acute and long-term morbidity

A

The use of antenatal steroids and postnatal administration of endotracheal surfactant

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43
Q

Prematurity remains the most common causes

A

morbidity and perinatal death.

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44
Q

Clinical gestation: has 3 periods (3-trimesters = ~9-months), each lasting 3 months

A

(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

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45
Q

What happens in third trimester?

A

– 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)

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46
Q

What is the clinical term (due date)

A

Estimated Date of Confinement (EDC)

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47
Q

Actual in utero growth is what?

A

2 weeks less (fertilization to birth=38 weeks)

48
Q

What is the Nägele’s rule?

A
49
Q

What determines the fetus the size, age and date of delievery of 9 week old fetus?

A

Ultrasound measurements of the Crown−Rump Length (CRL) of the fetus determines size, age & date of delivery

50
Q

What is the CRL of 9 week old fetus?

A

4.2 cm

51
Q

9-Week-old Fetus: Ex vivo Structures

A

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
Q

What happens from 9 to 12 weeks

A
53
Q

What happens to the intestines during 9th to 12th week

A

The intestines go back in the abdomen & are not in the umbilical cord

54
Q

What is establised 9-12th week

A

Primary Ossification Centers are established (Cranium (skull) & Long Bones)

55
Q

What is fully grown at 9 to 12 week?

A

Upper limbs are fully grown compared to the lower limbs

56
Q

What develops and visible in 12th week

A

External male & female Genitalia develop & are visible by 12 weeks, but remain small

57
Q

What is 12 week old fetal physiology?

A
58
Q

At 9 weeks what happens to the liver?

A

At 9-weeks, Liver initiates erythropoiesis (making of RBCs: Red blood cells)

59
Q

At 12-weeks, erythropoiesis switches to _

A

Spleen

60
Q

What happens in 9th-12th with urine?

A

Urine formation begins & is discharged via urethra into the amniotic fluid in the amniotic cavity

61
Q

What happens to swallowing amniotic fluid?

A
  • 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
Q

12-Week Fetus Imaging Modalities:

A

Look for Cranio-facial defects

63
Q

16th week

  • When is the fetal growth the most?
  • What is smaller?
  • What contines to lengthen?
A
  • 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
Q

What happens to the limbs in 16 week fetus?

A
  • 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
Q

What is the size of 12 week old fetus, 38 week?

A
  • 2.5 inch
  • 20 inch
66
Q

What is happening 16th week?

A
67
Q

What is the fetal development of 17 week fetus

A
68
Q

Relationship between age and egg quality

A

Deterioration after age 30

69
Q

What happens during 17th to 20th week (5 months)

A
70
Q

T/f: during 17th - 20th week of fetus is growing super fast

A

FALSE: super slow

71
Q

What happens to featal movements during 17th to 20th week?

A

Fetal movements quicken; felt by the mother very often.

72
Q

Eyebrows and head hair are well-developed & properly visible When

A

20 week of age

73
Q

What happens to fat during 17th to 20th week?

A

Brown fat (root of the neck) for heat production at birth.

74
Q

What is formed during 17th to 20th week

A

Fetal uterus is formed and canalization of the vagina begins

75
Q
  • What is visible for female fetus at 17 to 20 weeks?
  • What happens in male fetuses?
A
  • Primordial ovarian follicles containing oogonia are visible.
  • In males, the testes descends, but remains in the posterior abdominal wall.
76
Q

By 20th week what happens to the skin?

A

the skin has greasy /waxy white substance, which has a cheese-like consistency, called the “vernix caseosa”

77
Q
  • What does the vernix do?
  • What is made up of?
A
  • 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
Q

What does the fetus have for the vernix to stick?

A

Fetus has fine downy hair(called lanugo), for vernix to stick.

79
Q

What occurs during 21-25th week?

A
80
Q

What happens to weight and what is detected in 21-25 weeks

A

Substantial weight gain; body proportions are well defined and fingernails are detected

81
Q

Wrinkled & translucent skin; pink to red because of blood
capillaries develop by what?

A

24 weeks

82
Q

What happens to eyes at 21-25 weeks

A
  • Rapid eye movements/blink−startle responses.
83
Q

What happens to lungs at 21-25 weeks

A

Lungs begin maturation: the secretory epithelial cells (type II pneumocytes) in the lung alveoli secrete surfactants

84
Q

What is surfactant?

A

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
Q
  • A 25 week old fetus bone prematurely may survive in NICU if what?
  • What is there a risk for?
A
  • 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
Q

What happens during 26-29 weeks?

A
87
Q

What happens to Fetal Lung Development and Maturation: Week 26 onwards

A
88
Q

What happens at 30-38th week ?

A
89
Q

World Health Organization (WHO) Statistics on Premature Births

A
90
Q

Complications in Pregnancy: Maternal Mortality

A
91
Q

Last trimester

At full term, CRL = _ mm and Weight = _ g ( _ lb.)

A

At full term, CRL = 360 mm and Weight = 3400 g (7.5 lb.)

92
Q

What is happens in the last trimester?

A
93
Q

What are low birth weight causes?

A
94
Q

Major causes of IUGR (Intrauterine Growth Restriction):

A
95
Q
  • What is preterm neonates
  • What is postmaturity syndrome?
  • What are signs of fetal dysmaturity?
A
96
Q

What are some causes in low birth weight and high birth weight?

A
97
Q

What are other factors that influence fetal growth?

A
98
Q

Assessment of fetal status (26 weeks to 4 weeks after birth) is done by what?

A

perinatologists

99
Q

Methods employed for assessment:

A
  • (1) Diagnostic Ultrasonography
    – (2) Diagnostic Amniocentesis
    – (3) Chorionic Villus Sampling (CVS)
100
Q

What is dianostic ultrasonography?

A
101
Q

What is diagnostic amniocentesis?

A
102
Q

What is the Diagnostic Value of Amniocentesis

A
103
Q

What is Chorionic Villus Sampling (CVS)

A
104
Q

What is congential malformations (birth defects)

A

developmental anomalies or disorders that show anatomical/strucural or mental abnormality at birth

105
Q

What are is the leading casue of infact mortality?

A

birth defects

106
Q

What are some birth defects (5)

A
107
Q

What is Teratology

A

Principles of [Embryology + Pathology + Toxicology] to understand & classify developmental defects of malformed embryos and fetuses.

108
Q

What is Teratology (concept)”

A

Certain stages of embryonic development are more sensitive to “factors” that disrupt normal growth.

109
Q

Effect of Teratogens depend on:

A
  • Critical periods of development
    – Dose of the drug or chemical
    – Genetic background of the embryo
110
Q

What is a earlier medical belief?

A

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
Q

What is Congenital Rubella Syndrome

A
112
Q

Congenital Rubella Syndrome: Eye anomalies:

A
113
Q

What is the background of thalidomide?

A
114
Q

What is spina bifida cystica?

A
115
Q

What are the Classification of the causes of birth defects

A

Embryology: Summer Semester (10 decks)

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