Embryology Flashcards Preview

Hugh's MD1 Abdominal > Embryology > Flashcards

Flashcards in Embryology Deck (89):
1

What is the stomodeum?

Thin barrier that will become the mouth

 

1

Most of the urogenital system is formed from what? What isn't?

Intermediate mesoderm

Bladder and urethra

2

What is the issue with ectoderm taking over control of regulating limb development?

It is only one layer thick > easily damaged > damage leads to malformation

3

Somites split into 3 layers, what are they called?

Sclerotome (>bone of axial skeleton)

Myotome (>muscle)

Dermotone (>dermis of skin)

3

What is the function of the allantois in most developing mammals?

Stores nitrogenous waste

3

When does the small bowel move out into the body stalk and when does it retract?

Week 6-7 and week 9 respectively

3

What causes sinus invertus?

Cilia on the primitive node of the primitive groove don't beat correctly sending TFs and other developmental factors a random direction (instead of right to left)

4

Why don't human use their yolk sack?

All nutrients are provided the mother

4

Where does the urorectal septum lie?

Between the allantois and hindgut

5

What is the 16 cell stage called?

Morula

5

What is the name of the defect where the urogenital folds don't properly fold?

Hypospadiasis

 

6

Abnormalities in which broad factors can lead to birth defects?

Genes

Metabolism - deficiency in requirement

Intrauterine environment

Chromosome

Teratogen

6

At what stage is all major organogenesis finished?

3 months (first trimester)

7

What is the name of the cavity in the blastocyst?

Blastocoele

7

What is amelia?

Absent limb

7

What is the most critical period for development of birth defects?

First month

8

What is derived from the intermediate mesoderm?

Urogenital system

8

Why are the pharyngeal arches important?

Because they go on to form a multitude of different structures in the face and cervical region therefore defects in them have a large impact

9

What do neural crest defects result in?

Cleft palate defects

10

Which opens first the stomodeum or the proctodeum?

The stomodeum (mouth one)

11

What is the rate of cleft palate defects?

1:1000

11

Which germ layer initiates limb development?

Mesoderm

12

What is the proctodeum?

The thin barrier that will become the anus

13

Fusion of what causes the penis?

Urogenital folds 

14

What is the frequency of birth defects?

1:33 in live births

14

What is the rate of hypospadiasis?

1:300

16

What part of the blastocyst goes on to form the embryo?

Inner cell mass

18

How does the fertilised egg get down the fallopian tube?

Cilia action

18

What are the three germ layers?

Ectoderm

Mesoderm

Endoderm

19

What is the notochord?

Stiffened rod that runs down the midline in the developing embryo

20

Endoderm is always found with what?

Mesoderm

21

At the 20 somitomere stage, at what number do the somites start breaking off?

8, (1-7 stay attached and become the head)

22

What is the name of the structure that becomes the regulator of limb development?

Apical ectodermal ridge

22

What is the rate of limb malformations?

1:500

23

What is a failure of the gut to retract back into the body cavity called?

 

Omphalocoele 

 

24

What is the name of genetic congenital hip malformation?

Acetabulum malformation

26

Where do neural crest cell come from?

On top of the neural tube

27

The superior mesenteric artery act as what for the developing gut?

Axis of rotation

29

When to inner cell mass splits into 2, only one part goes on to develop into the embryo, which one is that?

Epiblast

30

Two tubes are formed in the purse string closure of the embryo, the primitive gut and the ...?

Coelom

31

When does the flapper valve in the atria close?

Upon taking the first breath

32

Will a heart defect abort a foetus in utero?

No, only become a problem after birth

33

Why ventricular defects occur?

The foramen present in utero doesn't close over properly

34

What is the failure of the abdominal wall to seal after retraction of the gut called?

Umbilical hernia

35

The trophoblast of the blastocyst becomes what?

The life support system of the embryo

37

What are somites?

Broken off, free floating somitomeres

39

 What is gastrulation?

The splitting of the inner cell mass into 2 then 3 layers

40

What does the lateral mesoderm split into?

Somatic and Splanchic mesoderm

41

At what day does the heart start developing?

22

42

How does the liver, lungs, pancreas and trachea develop off the developing GIT?

Outpocketing of endoderm that interacts with mesoderm

44

Splitting of the ectoderm ridge results in what?

Diplopodia

46

What are crest palate defects due to?

Failure of neural crest cells to migrate completely to the midline of the face

47

What are mesenchymal cell like?

Free moving, with associated connective tissue (opposite to epithelial cells)

 

49

What does the notochord do to the overlying ectoderm in the early embryo?

Direct it to developed into the neural plate - the precursor to the nervous system

50

What is the limb field?

A patch of mesoderm that goes on to develop into the limbs

51

What is most of the heart derived from? Be specific

Lateral splanchnic mesoderm

52

At what stage does the blastocyst implant in the uterine wall?

5-10 days

53

What is the name of the structure that the kidneys and ureters are derived from?

Mesonephros

54

What does the urorectal septum do?

Separates the allantois and hindgut as it travels to the cloacal membrane

55

What is the most common birth defect?

Heart defect 1:200

56

What is it called when apoptosis fails leaving fused fingers?

Syndactyly

57

What two germ layers make up the viscera? (be specific)

Splanchnic mesoderm

Endoderm

58

How are digits formed?

Apoptosis of symmetrical disc between where fingers will form

59

How does the foetus compensate for the small bowel growing too long?

It extends into the body stalk

60

What do neural crest cell become?

Peripheral nervous system tissue

Schwann cells

Melanocytes

Dentine

Facial bone, skin, muscle

61

What is the cloacal membrane?

Primitive seal of the anus

62

What is derived from endoderm?

Epithelium of gut, lung, liver, pancreas and associated organs

63

What is the name of the structure that undergoes cavitation at day 4?

Blastocyst

65

What are the most common heart defects?

Venticular defects (25%)

66

What organ is slowest to develop?

Brain

67

The embryonic mesoderm is divided into three sections, what are they called.

Paraxial (medial)

Intermediate

Lateral mesoderm

68

Which part of the limb field can be removed but compensated for?

The free limb patch

70

What are the names of the two tubes that become the heart?

Endocardial tubes

71

What is derived from ectoderm?

Neural tissue 

Epidermis

72

Which germ initiates and which germ layer finishs limb development?

Mesoderm and ectoderm respectively

73

What does the allantois become in humans?

The bladder and urogenital tract

74

What is derived from mesoderm?

Kidneys

Heart

Muscle

Most bones

Blood and vessels

Connective tissue

Gonads

Dermis of skin

Urogenital tract

Wall of gut and resp tract (but not epithelium)

76

What does the neural plate do?

Fold to form the neural groove

77

Of the 3 kidney pairs that develop, only one is used for the kidneys. What is the the second pair recycled for?

The ductus deferens from the mesonephric duct

79

What is meromelia?

Limb defect where hand or foot is present on a shortened limb

80

What are somitomeres?

Swelling of paraxial mesoderm running down laterally

81

What is the coelom?

Hollow space around the viscera

82

What is derived from the lateral mesoderm?

Heart

Blood

Limb skeleton

Ventrolateral body wall

Wall of gut and resp tract

Visceral peritoneum and pleura

83

What brings the colon into its normal place?

Twisting of the small bowel pulls it down

85

What two germ layers become the body wall? (be specific)

Ectoderm 

Somatic mesoderm

86

Which part of the developing gut remains connected to the yolk sack?

Midgut

87

When in embryonic development does limb development begin?

End of fourth week

88

What sets right-left asymmetry of (some) of the visceral?

The action of cilia in the primitive groove controlling the direction of transcription factor flow

89

What is sinus invertus?

Inversion of the viscera so that they are on the opposite side