Mod 1: Embryology Flashcards

1
Q

Embryo

A

Weeks 3-8
Gastrulation
Neurulation
Head, tail fold

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2
Q

Fertilization time

A

Beg week 1

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3
Q

Implantation time

A

End week 1

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4
Q

Bilam germ disc time

A

End week 2

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5
Q

Gastrulation time

A

Week 3

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6
Q

Head tail fold time

A

Weeks 4-5

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7
Q

Immature fetus

A

Weeks 9-25

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8
Q

Premature fetus

A

Weeks 26-36

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9
Q

Full term fetus

A

Weeks 37-38

St dev 12 days

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10
Q

Congen malform: zygote

A

Prenatal death

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11
Q

Congen malform: 3-14 weeks

A

Major morph malformation

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12
Q

Congen malform: 15-28 weeks

A

Minor abnormalities and functional deficits

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13
Q

Full term

A

38 weeks or 266 days

St dev 12 days

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14
Q

End of first trimester

A

All major organ sys

Length of Palm

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15
Q

Second trimester

A

Long as hand

50% survival at 22 weeks

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16
Q

Female infertility

A

Occlusion of uterine tube lumen

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17
Q

Male infertility

A

Low sperm count

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18
Q

Meningocele

A

Herniation of membranes around sc

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19
Q

Menungomyelocele

A

Herniation of membranes and sc

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20
Q

Surface ectoderm becomes

A

Epithelium
Hair
Nails
Cutaneous and mammary glands

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21
Q

Neuroectoderm becomes

A

Neural tube–> CNS

Neural crest –> dorsal root ganglia and nerves, pigment cells

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22
Q

Paraxial mesoderm

Somites form:

A

Muscles of trunk and limbs
Axial skeleton bone and cartilage (except head)
Connective tissue

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23
Q

Lateral plate mesoderm forms

A

Skelton of limbs

Connective tissue of muscles and viscera

24
Q

Zygote

A

Weeks 1-2
Fertilization
Implantation
Bilam germ disc

25
Q

Differentiation of mesoderm into what layers?

A

Paraxial
Intermediate
Lateral

26
Q

First evidence of limb buds on what day?

Major features of limbs present by…?

A

first evidence: day 26 (end of 4th week)

major features: end of 8th week

27
Q

Carnegie stages

A

standardized set of embryonic stages based on appearance of structures during development

28
Q

Forelimb or hindlimbs develop earlier? how much earlier?

A

Forelimbs precede by 1-2 days

(both forelimbs and hindlimbs present by 28 days

29
Q

What tissue initially forms limb bud?

A

somatic lateral plate mesoderm (helps form body wall) covered with ecotoderm

30
Q

What levels does forelimb/hindlimb develop?

A

Forelimb: caudal, cervical (C4-T2 – about same as brachial plexus)
Lower limb: lumbar and upper sacral (L2-S3)

31
Q

Limb bud elongates in what direction?

A

proximal –> distal

32
Q

When do hand and foot plates form?

A

hand plates: 6th week

foot plates: 7th week

33
Q

Describe formation of digital rays?

When?

A

mesenchyme in plates condenses to form digital rays
proliferation and apoptosis – fingers and toes
by end of week 8

34
Q

Chondrification
Osteogenesis
Endochondral ossification

A

Chondrification (5 w): development of cartilaginous precursor which will later undergo osteogenesis to form bone (7 w)
Endochondral ossification: develop primary ossification centers to replace cartilage

35
Q

When do secondary ossification centers form?

A

birth

36
Q

What genes/TF’s in limb development are highly conserved across animals?

A

Hox (gene)

TBX 4 and 5 (transcription factors)

37
Q

Haploinsufficiency

A

patients have one working copy of gene (mutations in both copies would be lethal) – why diff from animal models

38
Q

Phenocopies

A

malformations have diff causes, but have same physical result

39
Q

Unilateral deformation of limb suggests what cause?

A

pressure on limb

if genetic, would likely be bilateral

40
Q

What measures used to determine age of fetus?

A
Crown Rump Length (1st trimester)
2nd and 3rd trimesters:
Head circumference/diameter
abdominal circumference
femur length
foot length
41
Q

Viability

A

ability of fetus to survive in extrauterine environment

42
Q

Immature infants

Premature infants

A

immature: fetuses with extremely low birth wt (less than 500 g) – don’t survive
premature: fetuses with very low birth wt (b/w 1500-2500 g) – survive with complications

43
Q

When does fetus reach 500 g?

1500g?

A

500g: week 23
1500g: week 29

44
Q

Premature deaths due to

A

incomplete differentiation of CNS and resp sys

45
Q

Factors influencing fetal growth

A

maternal
fetal
environmental

46
Q

Primary source of maternal substrate for fetal growth

A

maternal glucose

fetal insulin used for metabolism of glucose

47
Q

What stimulates fetal growth?

post natal growth?

A

Fetal: insulin-like growth factor

Post-natal: human growth hormone (IGF later becomes human growth hormone)

48
Q

IUGR

What causes it

A
Itraunterine growth retardation (low birth wt)
smoking
alcohol
drugs
poor nutrition
poor fetoplacental bloodflow/placental dysfunction
genetic factors
twins
49
Q

What period is most suceptible to factors causing problems?

A

embyronic

50
Q

Malformation

A

errors in genetic programming/tissue formation

51
Q

Deformation

A

forced into abnormal shapes

52
Q

Disruptions

A

targeted, localized insult

53
Q

Syndrome

A

group of anomalies occuring together with common cause

54
Q

Perinatology

A

assess health of fetus and newborn (26 wks - 4wks old)

55
Q

Methods for assessing health of fetus

A
ultrasound
fetoscopy
CT
MRI
xrays (amniography, fetography)
amniocentesis (vest after wk 12) -- collect alpha fetoprotein, genetic disorders
alpha fetoprotein assay
sex chromatin analysis
cell culture
chorionic villus sampling
percutaneous umbilical cord blood sampling