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Reproduction, Development and Ageing > 6. Development > Flashcards

6. Development Flashcards

1
Q

What is a cleft palate?

A
  • Connection between the mouth and the nasal cavity
  • 2 components haven’t fused at the centre to form the hard palate
  • Causes problems with breathing, eating and drinking
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2
Q

Is foetal mal-development more likely to be genetic or environmental?

A

Genetic (but even more likely to be multifactorial)

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3
Q

What infectious agents can cause mal-development?

A
  • Rubella e.g. cataracts
  • HSV e.g. microcephaly
  • HIV e.g. microcephaly
  • Syphilis e.g. mental retardation
  • Zika e.g. microcephaly
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4
Q

What physical agents can cause mal-development?

A

X-rays and other ionising radiation e.g. microcephaly, cleft palate etc.

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5
Q

What chemical agents can cause mal-development?

A
  • Thalidomide e.g. limb defects
  • Lithium e.g. heart malformation
  • Amphetamines e.g. cleft lip
  • Cocaine e.g. growth restriction
  • Alcohol e.g. foetal alcohol syndrom
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6
Q

When is the CNS vulnerable to teratogens?

A

Whole of development

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7
Q

Do teratogens impact development in the first couple of weeks?

A

No, but the foetus would just be miscarried (not a teratogenic effect)

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8
Q

What is chimerism?

A

2 genetically distinct conceptuses combine to form one individual - no issues

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9
Q

What is mosaicism?

A

Differences in genetic makeup between cells within one individual

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10
Q 
What are the effects of the following chromosome abnormalities:
• Klienfelter's syndrome (XXY)
• XYY
• XXX
• XXXX
A
  • Klienfelter’s syndrome (XXY) - decreased fertility
  • XYY - variable (taller, learning problems)
  • XXX - limited effects, some mental changes
  • XXXX - severe effects
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11
Q

What problem determines survival in Down’s syndrome (Ch21)?

A

Heart problems

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12
Q

What is prognosis like for foetuses with Edward’s (Ch18) and Patau’s (Ch13) syndrome (both trisomy)?

A

Most die before birth

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13
Q

Has Ch1 trisomy ever been found in pregnancy loss tissues?

A

No

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14
Q

What is Turner’s syndrome?

A
  • XY linked - X0 (lost chromosome)
  • Female, short stature, infertile
  • Y0 is not viable as boys need the X chromosome
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15
Q

Are there any autosomal syndromes involving the loss of a chromosome?

A

No, but partial chromosome loss syndromes are known

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16
Q

Give an example of a genetic condition seen in animals and humans

A

Piebaldism
• Mild mutation of the KIT receptor
• Mouse can have pale patch of fur
• Human can have pale streak on forehead

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17
Q

What is Holt-Oram syndrome?

A

Due to mutation in TBX5 (TF) - required as both structures develop

  • Structure of the heart and division between the chambers doesn’t develop properly
  • Heart becomes bigger
  • Lack of symmetry in the left and right hand
  • Thumb can become a finger
18
Q

What is Achondroplasia?

A

Gain of function mutation in FGFR3

  • Conversion of cartilage to bone
  • Lack of bone growth in long bones
  • Achondroplastic dwarfism
19
Q

What is Polydactly?

A
  • Extra digit
  • Duplication of digital rays (have 6 not 5)
  • Webbing may stay put - extra digit has formed too close
20
Q

When do the limbs form in a foetus?

A
  • Forelimb bud - day 27/28
  • Hindlimb bud - day 29
  • Grows from the lateral plate mesoderm
  • Digits are fully formed and patterned by day 56
21
Q

What are the 2 types of gaps in a cleft lip?

A

Unilater or bilateral (has bigger gap)

22
Q

In how many places can there be a cleft palate?

A

1 - midline

23
Q

Does the cleft palate and lip need to be mended?

A
  • Cleft palate must be mended to prevent food from entering the nasal cavity and lungs
  • Cleft lip repair is important for cosmetic and psychological reasons
24
Q

How well does a mended cleft palate/lip repair?

A

Well as cells in babies proliferate quickly with little scarring

25
Q

What are the 3 forms of spina bifida?

A
  • Hidden form (CNS is ok, but spine hasn’t formed correctly) - spina bifida occulta
  • CSF filled swelling - meningocele
  • Swelling with nervous tissue - myelomeningocele
26
Q

Can surgery help spina bifida?

A
  • Can help anatomical problems

* Can’t solve the functional problem

27
Q

When does spina bifida development take place?

A

Within the first 4 weeks (PF)

28
Q

How is spina bifida related to neurulation?

A
  • Transformation of neural plate into neural tube
  • Tube does not completely seal up in spina bifida
  • Due to bulge in CNS which stops complete formation
  • Forms posterior neuropore
29
Q

Which nutrient is important to prevent spina bifida and anencephaly

A

Folic acid

(should be given 3 months prior to conception, as the egg does most of it’s development before selection as the main follicle)

30
Q

What causes anencephaly?

A

Incomplete anterior neuropore closure

31
Q

When does anencephaly develop?

A

Around 23 days (PF)

32
Q

What is thalidomide and it’s significance in pregnancy?

A
  • Was used to treat Hyperemesis gravidarum in pregnancy
  • Found out to affect foetus limbs (mainly upper)
  • Also caused deformed eyes, deformed hearts, deformed alimentary and urinary tracts, blindness and deafness
  • 50% initial survival rate
  • Now used in some leprosy and cancer treatments
  • Cannot be given to women of reproductive age
33
Q

What polarising factor for limb development?

A

Sonic Hedgehog (shh)

34
Q

How does thalidomide cause limb defects?

A
  • One of the isoforms stops blood vessel development
  • Cell death results
  • Limbs are devoid of nutrients and truncates prematurely
35
Q

How does exposure time to thalidomide effect limb loss?

A
  • Short exposure - partial limb loss (Phocomelia)

* Longer exposure - complete limb loss (Amelia)

36
Q

What is respiratory distress syndrome (RDS)?

A
  • If a baby is born early, the lungs might not be developed enough
  • Lack of surfactant so surface tension can’t be reduced enough
  • Causes difficulty in breathing
37
Q

When does surfactant production begin?

A

26 weeks (post-fertilisation) = 24 weeks gestational age

38
Q

When is there enough surfactant in the lungs to be able to breath normally?

A

Only at term

39
Q

How can in utero production of surfactant be increased?

A

1 injection of glucocorticoids 2-3 days before delivery

40
Q

What is the chance of having respiratory distress syndrome if the baby is born at 24 weeks?

A

100%

Reproduction, Development and Ageing (7 decks)

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