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LECOM MS1 Embryology > Embryonic and Fetal Period (Exam 1) > Flashcards

Embryonic and Fetal Period (Exam 1) Flashcards

1
Q

When is the embryonic period

A

weeks 3-8

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2
Q

How is the age of the embryo expressed in the beginning of the embryonic period

A

number of somites presented

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3
Q

How is the size of embryo measured

A

crown rump length

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4
Q

How is crown rump length measured

A

vertex of the skull to the caudal tip of the trunk

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5
Q

During what period will organogenesis occur

A

embryonic

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6
Q

What are the derivatives of the trilaminar embryo

A

ectoderm
mesoderm
endoderm

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7
Q

What will the ectoderm go on to form

A

outside stuff and nerves

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8
Q

What will the mesoderm form

A

bones, urinary, genitals, CT

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9
Q

What will the endoderm go on to form

A

GI and organs

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10
Q

What germ cell layer is epithelium derived from

A

All 3 layers

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11
Q

What part of the epithelium is formed from the mesoderm

A

vascular endothelium

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12
Q

What part of the epithelium is formed by the endoderm

A

epithelium of structures from yolk sac

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13
Q

What part of the epithelium is formed by the ectoderm

A

epidermis and ependyma

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14
Q

How are epithelial tumors derived from mesoderm named

A

Benign: angiomas
Malignant: sarcomas

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15
Q

How are epithelial tumors derived from endoderm named

A

Benign: papilloma/adenoma
Malignant: carcinomas

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16
Q

How are epithelial tumors derived from ectoderm named

A

Benign: papilloma/adenomas

Malignant: carcinomas

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17
Q

What layers are connective tissue derived from

A

mesoderm for torso and limbs

neuroectoderm for head

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18
Q

How are connective tissue tumors named:

A

Benign: lipoma, fibroma, chondroma, osteoma

Malignant: sarcomas

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19
Q

What layer is muscle derived from

A

mesoderm

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20
Q

How are muscle tumors named

A

Benign: myoma
Malignant: myosarcoma

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21
Q

What layer is nerve derived from

A

neuroectoderm

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22
Q

What germ layers are teratomas derived from

A

all three layers
ectoderm
endoderm
mesoderm

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23
Q

What is neurulation

A

formation of the neural tube from the neural plate

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24
Q

What forms the neural plate

A

ectoderm thickens

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25
Q

When does the neural plate begins to fold

A

day 20

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26
Q

When does the neural folds make first contact in the cranial end

A

Day 22

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27
Q

Fusion of the neural plate occurs in what direction

A

caudal and cranial directions

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28
Q

When does the cranial neuropore close

A

Day 24-25

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29
Q

When does the caudal neuropore close

A

Day 26-27

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30
Q

Fusion of the neural folds results in formation of what

A

the neural tube

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31
Q

What is a neuropore

A

temporary embryonic openings between neural canal and amniotic cavity

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32
Q

What layer is the neural tube derived from

A

ectoderm

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33
Q

What is secondary neurulation

A

invagination of surface ectoderm that forms the sacral and coccygeal spinal cord

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34
Q

What is formation of the sacral and coccygeal spinal cord associated with

A

tethered cord syndrome

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35
Q

What are neural crest cells

A

cells that migrate away from the ectoderm after neurulation, dissociate and migrate to the respective locations

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36
Q

What are the neural crest derivatives

A 
parasympathetic ganglia
sensory ganglia
autonomic and dorsal root ganglia
CT around eye
optic nerves
muscles of the pupil and ciliary body
mesenchyme of the head
pia and arachnoid mater of the occipital region
structures in the pharyngeal arches
dermis, smooth muscle and fat of the face
odontoblasts
Schwann cells
chromatin cells of the adrenal medulla
neurosecretory cells of the heart and lungs
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37
Q

What will surface ectoderm give rise to

A 
epidermis, hair, nails
cutaneous and mammary glands
anterior pituitary gland
enamel of teeth
internal ear
lens of eye
ectodermal placodes
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38
Q

List the layers of intraembryonic mesoderm formed on either side of the notochord

A

paraxial mesoderm
intermediate mesoderm
lateral plate mesoderm

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39
Q

What is derived from the paraxial mesoderm

A

form the axial skeleton, the vast majority of skeletal muscle, and associated CT and dermis

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40
Q

What is derived from the intermediate mesoderm

A

the GU and genital system

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41
Q

What will the lateral plate mesoderm form

A

splits into two layers

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42
Q

What layer of mesoderm will form somites

A

paraxial mesoderm

43
Q

How does the paraxial mesoderm form somites

A

forms somitomeres in a segmental fashion that will develop further into somites

44
Q

When is the 1st somite formed

A

day 20

45
Q

How many somites does embryo have in total

A

42-44

46
Q

What occurs to the somites though

A

disappear at caudal end leaving 37 pairs

47
Q

What do the first 7 somitomeres form

A

NOT somites. Rather structures in head and neck

48
Q

What will the first 4 somites give rise to

A

development of occipital part of skull, the bones that form the nose, orbit and musculature of the tongue

49
Q

Where do somites 5-12 form

A

in the cervical region

50
Q

Where and what do somites 12-24 form

A

in the thoracic region to form thoracic vertebrae and musculature and bone of thoracic wall and abdominal wall

also forms structures of the upper limb

51
Q

What do lumbar somites form

A

abdominal dermis, muscles, vertebrae, and structures of lower limb

52
Q

What will somites differentiate into after the 4th week

A

dermatomyotomes and

sclerotomes

53
Q

What are dermatomyotomes

A

splits into dermatome and myotome

54
Q

What is a dermatome

A

skin supplied by single spinal nerve

55
Q

What is a myotome

A

muscle supplied by a single spinal nerve

56
Q

What is sclerotome

A

area of bone or fascia supplied by a single nerve root

57
Q

Where is vasculature derived from

A

mesoderm

58
Q

What are the two stem cells of the mesoderm

A

hemangioblasts

hemopoietic stem cells

59
Q

What do hemangioblasts do

A

give rise to blood vessels

60
Q

What do hemopoietic stem cells do

A

give rise to blood cell precursors

61
Q

What are capillary hemangiomas

A

collections of blood vessels typically associated with the face

62
Q

How common are capillary hemangiomas

A

10% of all pregnancies

63
Q

What layer of the embryo contributes to the yolk sac

A

endoderm

64
Q

What are the membranes that bind the primitive gut tubes at the ends

A

cloacal membrane

buccopharyngeal

65
Q

How is the cloaca formed

A

lateral folding of embryo incorporates allantois leading to cloaca formation

66
Q

What is the vitelline duct

A

tube that provides nutrients to the midgut from the yolk sac during gestation

67
Q

What type of folding leads to formation of primitive gut tube

A

longitudinal

68
Q

What parts of the primitive gut tubes are formed from longitudinal folding

A

foregut, midgut, and hindgut all lined by endoderm

69
Q

What are the derivatives of endoderm apart from epithelial lining of the GI tract and allantois

A

eptithelium of respiratory tract, bladder, urethra, tympanic cavity, and auditory tube

parenchyma of the thyroid, parathyroid, liver, and pancreas

stroma (supportive CT) of the tonsils and thymus

70
Q

When is the fetal period

A

weeks 9-38 (or birth)

71
Q

What are characteristics of the fetal period

A

external form of developing human, presence of major organ systems

rapid growth and further development of organ systems

fetus becomes viable during this period

72
Q

What are the methods of determining fetal age

A

expected date of confinement (EDC)

gestational age

last normal menstrual period

actual date of fertilization

73
Q

What is the expected date of confinement

A

uses measures of CRL measurements and femur length to determine age

74
Q

What is gestational age

A

age from the last mensturation (NOT conception)

75
Q

What is LNMP age

A

measure gestation takes approximately 40 weeks

76
Q

What is actual date of fertilization

A

with this measure gestation takes 38 weeks

77
Q

What are the main highlights of the 1st trimester

A

all major systems developed

78
Q

What are the main highlights of the 2nd trimester

A

external anatomy, many birth defects can be detected

79
Q

What are the main highlights of the 3rd trimester

A

fetus becomes viable

80
Q

Highlights of weeks 9-12

A

liver is major site of erythropoeisis

external genitals can be distinguished

81
Q

What are the highlights of weeks 13-16

A

sites of ossification evident
eye movements
eyes facing forward

82
Q

What are the highlights of weeks 17-20

A

primary oocytes formed

testes start descending

83
Q

What are the highlights of weeks 21-25

A

Surfactant begins to be secreted

prevents alveoli in lungs from collapsing by relieving surface tension

84
Q

What are the highlights of weeks 26-29

A

Lungs can now breath
CNS can control breathing and temp
Spleen is still making blood cells, formation starts shifting to bone marrow

85
Q

When will formation of blood cells shift to bone marrow

A

After delivery

86
Q

What are the highlights of 30-34

A

pupillary light reflex, fat still accumulating

87
Q

What are the highlights of weeks 35-38

A

finishing period
final prep of tissues
important to transition to the outside world

88
Q

During the first 12 weeks what is major site of blood cell production

A

yolk sac

89
Q

What is the major organ of hemopoeisis

A

liver

90
Q

WHen does the spleen start making blood cells

A

week 12

91
Q

When does bone start making blood cells

A

by week 30

92
Q

What are possible reasons to perform amniocentesis

A 
if mother has past downs child
mother is of advanced age
parents carry chromosomal abnormalities
parents are x-linked carriers
history of neural tube defects
parents have inborn errors of metabolisms
93
Q

What layers are transversed in amniocentesis

A

Body wall
Faschia
Chorion: (syncytiotrophoblast, cytotrophoblast, mesoderm), amniotic sac

94
Q

What is the presence of high levels of alpha-fetoprotein indicative of

A

body wall or neural tube defects

95
Q

What is the presence of low levels of Alpha fetoprotein in maternal serum indicative of

A

depressed in the maternal serum in Down syndrome and Trisomy 18

96
Q

What is spina bifida

A

neural tube defect marked by congenital cleft of the spinal column

97
Q

What does spina bifida show usually

A

protrusion of the meninges and sometimes the spinal cord

also note the tuft of hair on the back

98
Q

What region do the neural tube folds first make contact

A

area of the four occipital somites and first cervical somite

99
Q

What is secondary neurulation

A

invagination of surface ectoderm that forms the sacral and coccygeal spinal cord

100
Q

When is secondary neurulation completed

A

by day 42

101
Q

Somites give rise to most of what

A

axial skeleton

voluntary muscles of the neck, body wall and limbs, and to part of the dermis of the neck and trunk

102
Q

The first 4 somites contribute to what

A

development of occipital part of the skull, the bones that form the nose, orbit, and musculature of the tongue

103
Q

What is vasculogenesis

A

formation of new blood vessels

104
Q

What is angiogenesis

A

sprouting from existing vessels

LECOM MS1 Embryology (19 decks)

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