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Flashcards in Development Deck (92)
1

what controls limb development after the initial budding of the mesoderm

ectodermal ridge

1

what does thalidomide cause

amelia and meromelia

1

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

umbilical hernia

2

apart from the bladder and urethra, the rest of the urogenital tract is formed from the..

intermediate mesoderm

3

when does the blastocyst implant into the uterine wall

between 5-10 days

3

what is the commonest congenital heart defect

ventricular septal defect

3

what causes sinus invertus

complete failure of the cilia of the primitive node - pure change whether organs are set properly or back to front

4

what is the neural crest

the cells at the point of fusion of the neural tube

4

what is the yolk stalk

that part of the yolk sac that is still connected to the gut lumen that persists until it is finally pinched shut

4

what happens to the urorectal septum

it extends towards the cloacal membrane to divide the rectum from the urogenital tract

5

order of endoderm, ectoderm and mesoderm from top to bottom of the blastocoele

ectoderm mesoderm endoderm

6

two cell populations in the blastocyst

inner cell mass

trophoblast

8

what structural feature determines morula from blastocyst

blastocyst undergoes cavitation to form a cavity = blastocoele

9

what is the morula

16 cell stage of the embryo

10

what is the cause of congenital hip dislocation

the acetabulum is malformed

- can be due to genetic or mechanical problems in utero

11

fate of the neural crest?

cells migrate off and leave the neural tube to form elements of the nervous system that dont form the CNS, and the other random things

12

what happens to the inner cell mass

- first splits into epiblast and hypoblast

- then epiblast will splits into 3 layers - ectoderm, endoderm and mesoderm

12

what lies between the allantois and the hind gut

urorectal septum (part of the mesoderm)

14

how many live births have a birth defect

1:33

14

how do the trachea, lungs, liver and pancreas initially appear

as endodermal out-pocketings interacting with the mesoderm

15

how many pharyngeal arches are there

4

16

what is amelia and meromelia

amelia - absent limbs

meromelia - reduced limbs

16

how is the gut tube made

yolk sac separates from the embryo --> due to this some of the endoderm is pinched off

17

which tissues does the intermediate mesoderm give rise to

urogenital system

17

where does the heart develop from

the lateral splanchnic mesoderm

17

what causes VSD

when the intraventricular foramen is not filled by membranous part of IVS

18

what are somitomeres

swellings of the flat sheet of paraxial mesoderm lateral to the neural tube on both sides

19

components of the mesonephros

pronephric duct of the pronephros becomes the mesonephris duct with mesonephric tubules

20

what is the zygote

the single fertilized egg

20

how does the large intestine get to the right position in the body

it is pulled there by the rotation and lengethening of the small intestine

21

at what time of genstation does the mouth open to the outside

at 3 weeks --> ectoderm meets ectoderm (still present in humans - stratified squamous of mouth to respiratory epithelium that linkes pharynx)

22

what does the rest of the epiblast (that doesnt contribute to the embyro) and all of the primitive hypoblast give rise to

extra embryonic tissue

23

what happens to the mesonephric duct

- males --> redeployed and becomes the vas deferences

- females --> throw it away

24

which tissues does the lateral mesoderm give rise to

- ventrolateral body wall

- limb skeleton

- visceral pleura and peritoneum

- blood vessels and blood forming tissue

- heart

- wall of gut and respiratory tissues

25

what does mesenchyme refer to

ells that are isolated from each other, that are freely moving, and often have CT between cells

26

associations of the somatic and splanchnic mesoderm

somatic mesoderm associated with the ectoderm

splanchnic mesoderm associated with the endoderm

27

what happens to the allantois

gives rise to the bladder and urogenital tract

28

how is the penis formed

from the fusion of the urogenital folds

29

which forms first? the urinary system or the genital system

urinary system

30

what is the 1st identifiable structure that forms in the 3 layers of the epiblast

the notochord

32

what does the mesoderm give rise to

- dermis, blood, heart and BVs, kidneys and urogenital tract, gonads, most bones and muscles, and CT, walls of gut and respiratory tract (not lining), pleura, peritoneum, pericardium

33

what forms the fallopian tubes, the uterus and the upper 2/3 of the vagina in girls

the Mullerian duct

35

when does the blastocyst form

4 days

36

what is the bilaminar disc

epiblast + hypoblast

37

how does the allantois form

as a branch of the hind gut

38

failure of apoptosis of the cells between fingers can lead to

webbing or syndactyly (fused fingers)

38

what is the first sign of the appearance of the coelom

the split of the lateral mesoderm into somatic mesoderm above and splanchnic mesoderm below

39

neural crest derivatives

- dorsal root ganglia - sympathetic and parasympathetic ganglia - enteric ganglia - schwann cells - melanocytes - dentine - muscle, cartilage, and bone of skull, jaws, face and pharynx - outflow tracts of the heart (bottom 3 not part of the nervous system)

40

from what layer of the epiblast is the notochord derived from

mesoderm

42

what is the most common birth defect

heart defects

42

which part of the mesoderm becomes the appendicular skeleton

lateral mesoderm

43

what initially closes the gut tube to the outside world

mouth end = stomodeum

anus end = proctodeum and cloacal membrane (thin layers of ectoderm)

45

which part of the inner cell mass becomes the embryo

part of the epiblast

46

when do limbs start development

at the end of the 4th week as a little bud of mesoderm

48

which parts of the heart are developed from the neural crest

- parts of midline

- major outflow vessels

50

what does the endoderm give rise to

epithelium of the gut and associated organs

51

at what time in gestation is the morula

3 days

52

names of the 3 pairs of kidneys made during development

pronephros

mesonephros

metanephros

53

how do the commonest congenital heart defects form

as a failure of the fusion of the chambers of the heart

55

how does the epiblast split into 3 layers

by gastrulation

57

at what stage of somitomere development does one somitomere become independent

at the 20 somitomere stage

58

explain the heart development

forms a tube bilaterally --> bought together in the midline underneath the gut (between gut and ventral wall) --> fuse to produce 2 chambers (1 atria and 1 ventricle) with 2 outflows and 2 inflows --> heart then folded and fused to produce 4 chambers

59

where does the metanephros develop? and where does it migrate

at the bottom of the mesonephric duct --> moves upwards along the mesonephric duct

61

what do the sclerotome, dermotome and myotome become

sclerotome = axial skeleton

dermatome = dermis of skin

myotome = back muscles and limb muscles

62

what is hypospadiasis

failure of the urogenital folds to completely fuse in males --> leaving a urethral opening on the base of the penis

64

what happens if you remove the limb field

no development of the limb

65

when is the natural period of herniation

around week 6-8

67

what causes cleft lip and cleft palate

failure of the neural crest cells to completely migrate forwards and fuse and the midline of the face

68

components of the pronephros

neprostomes and pronephric duct

69

what do the somatic and splanchnic mesoderm become

somatic - muscle and CT

splanchnic - structures associated with viscera

70

which somitomere is the first to become independent as a somite, and where anatomically is it located

somitomere 8, at the neck

71

what causes defects in the outflow tracts of the heart

failure of migration of the neural crest cells

72

which tissues does the paraxial mesoderm give rise to

- dermis of skin

- axial skeleton

- axial and limb muscles

73

splitting of the mesoderm..

- paraxial mesoderm - medial to the notochord

- lateral mesoderm - most lateral to notochord

- intermediate mesoderm - in between paraxial and lateral

74

arterial supplies of the foregut, midgut and hindgut

foregut - ciliac artery

midgut - superior mesenteric artery

hindgut - inferior mesenteric artery

76

what does the trophoblast form

some extraembryonic structs (part of the placenta)

77

the dermomyotome splits again into

dermatome and myotome

77

what allows the gut to undergo rotation when undergoing rapid growth

the yolk stalk

78

function of the notochord

to induce overlying ectoderm to form the neural plate (organises tissue around it)

79

what is the second most common birth defect

hypospadias (misplaced urethral opening in boys)

80

how are the finger and toe digits sculptured

apoptosis kills the cells in the bands between the presumptive fingers

81

what causes diplopodia

when the ectodermal ridge is damaged --> loss of control of growth

82

at what time in development does the gut retract back into the body cavity

by week 9

83

what does the somites do

splits into sclerotome and dermomyotome

85

failure to retract the gut back into the body cavity is called what

omphalocele

86

migration of the hypoblast

moves circularly around the blastocoele and encompasses the yolk sac

87

at what stage in development is major organogenesis complete?

by 3 months (end of the first trimester)

88

what does the ectoderm give rise to

nervous system and epidermis

89

folding of neural plate

folds around neural groove to form the neural tube

90

what is the anatomy of the limb field

central free limb field and peripheral tissue

91

what is the neural plate

patch of endoderm that is fated to become your nervous system

92

how are the body axes determined

- AP determined by the first cleavage of the zygote

- D-V determined by the position of the inner cell mass in the blastocyst

- L and R set along the longitudinal axis by the signals distributed by the cilia on the primitive node that swirls current from R to L