embryology Flashcards

1
Q

what is the ampula of the fallopian tube

A

the area where the fertilisation occurs

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2
Q

what is cleavage

A

this is when the zygote undergoes proliferation from one cell to sixteen

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3
Q

what is the marula

A

the hollow ball of 16 + cells formed after cleavage. the cells surround the outer edge of the circle, leaving a cavity in the middle

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4
Q

what are the cells of the marula called

A

blastomeres

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5
Q

what is blastulation

A

the process of when the marula becomes the blastocyst

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6
Q

what is the structure of the blastocyst

A

an outer cell mass, and inner cell mass that is compacted to one side, and an empty cavity with fluid in it

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7
Q

what does the outer cell mass of the blastocyst become

A

the trophoblast

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8
Q

what does the inner cell mass of the blastocyst become

A

the embryoblast

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9
Q

what does the trophoblast differentiate to become

A

cytotrophoblast and syncitiotrophoblast

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10
Q

what does the cytotrophoblast and syncitiotrophoblast develop into

A

the placenta

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11
Q

how does the blastocyst enter the uterus and stay there

A

as cleavage is occuring, the structure slowly moves along the fallopian tube and then into the uterine canal, and with the use of integrins and selectins it is able to hook onto the endometrium

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12
Q

what is the cytotrophoblast

A

these are the well defined cell margins of the trophoblasts

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13
Q

what happens to the cytotrophoblast

A

it begins to proliferate and distintigrate the cell membrane of the blastocyst to form a fluid from the nuclei and cytoplasm of the cells.

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14
Q

what is the synctium

A

pool of fluid containing the nuclei and fused cytoplasm of the cytotrophoblast cells

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15
Q

what is the synctiotrophoblast

A

the protrusion from the blastocyst created by the cytotrophoblast that contains the nuclei and cytoplasm of the cells. no well defined cell borders

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16
Q

what does the syncitiotrophoblast release

A

hydrolytic enzymes into the uterine lining

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17
Q

what does the syncitiotrophoblast become confluent with

A

the maternal blood vessels, and this allows the embryo to receive nutrients and oxygen from the mother - this is the development of the placenta

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18
Q

what is produced by the syncitiotrophoblast to prevent the endometrial lining from shedding, which in turn allows the embryo to continue living

A

beta human chorionic gonadotropin

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19
Q

what does beta human chorionic gonadotropin do

A

stimulates the corpus luteum to produce progesterone

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20
Q

what happens if progesterone levels drop

A

the blood vessels of the uterine lining start spasming, and they then rupture. the cells in the lining become nectrotic and shed

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21
Q

what does shedding of the uterine lining cause

A

shedding of the embryo

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22
Q

what is the bilaminar disc

A

this is formed from the embryoblast, and composes of two layers sandwhiched together. the top layer is epiblast and the lower is hypoblast. above the epiblast is the amniotic cavity, and below the epiblast is the yolk sac

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23
Q

what is the function of the yolk sac

A

help with red blood cell production and provide nutrients

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24
Q

what is the prochordal plate

A

this is where the epiblast and hypoblast are connected, and provides orientation of the anatomy as it is located at the cranial aspect of the embryo

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25
Q

which aspect of the embryo is furthest from the prochordal plate

A

the caudal aspect

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26
Q

what is the caudal aspect of the embryo

A

the tail

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27
Q

what is the name of the membrane by the caudal aspect of the embryo and what does it develop into

A

the cloacal membrane which becomes the butthole

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28
Q

what is the name of the membrane by the cranial aspect of the embryo and what does it develop into

A

the buccopharyngeal membrane which develops into the mouth

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29
Q

what is the primitive streak

A

a thickening of the epiblast layer of the bilaminar disc

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30
Q

what is the primitive node

A

a knob like structure toward the top of the primitive streak

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31
Q

what happens to the primitve streak

A

the cells in the centre begin to die

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32
Q

what does the primitive streak become when the cells die

A

the primitive groove

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33
Q

what does the primitive node become when the centre cells die

A

the primitive pit

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34
Q

what does the primitive groove secrete

A

fibroblast growth factor 8,

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35
Q

what does FGF8 do

A

move laterally from the primitive groove to the epiblast cells and binds to the receptor to trigger intracellular process

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36
Q

what is the intracellular process triggered from the binding of FGF8 to FGF-R on the epiblast cells

A

SNAIL-1 is secreted

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37
Q

what is SNAIL-1

A

a protein that inhibits the formation of E-cadherins

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38
Q

what do E-cadherins do

A

they stick cells together

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39
Q

what does the secretion of SNAIL-1 mean

A

the cells are no longer stuck together and they can migrate

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40
Q

what is epithelial migration

A

the movement of the epiblast cells

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41
Q

where do the epiblast cells migrate to

A

they migrate toward the primitive streak, and move down to the hypoblast layer to replace it, forming the endoderm

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42
Q

what does the hypoblast become

A

the endoderm

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43
Q

what happens after the formation of the endoderm

A

more epiblast cells are stimulated to move through the primitive groove and down and then forward, which forms the mesoderm

44
Q

what is the trilaminar disc

A

the product of the migration of epiblast cells to form the endoderm and mesoderm

45
Q

what is the process called when the bilaminar disc becomes the trilaminar disc

A

gastrulation

46
Q

what is gastrulation

A

the change from bilaminar disc to trilaminar disc

47
Q

what happens following gastrulation

A

more growth factor is released and the cells migrate through the primitive pit to the prochordal plate to form the notochord

48
Q

where in the trilaminer disc is there no mesoderm

A

the notochord
the cloacal plate
the prochordal plate

49
Q

in which direction does the notochord go

A

cranially

50
Q

what is the adult remnant of the notochord

A

the nucleus pulposus of invertebrate discs, found between the vertebrae

51
Q

what does the notochord do

A

release growth factors and proteins to stimulate the ectodermal cells to proliferate and thicken

52
Q

what does the thickening of the ectoderm result in

A

formation of the neural plate

53
Q

what happens to the neural plate

A

the central portion forms a divot, which creates a groove known as the neural groove. the top of the groove curves inward creating neural folds, which eventually meet and fuse to form the neural tube which buds underneath the ectoderm to lie in between the mesoderm

54
Q

why are neural folds important

A

they contain neural crest cells

55
Q

where are neural crest cells found

A

surrounding the edge of the neural tube

56
Q

describe the inital structure of the neural tube and what happens to it

A

either end has pores - anterior and posterior neural pores. they need follate to close, and should usually be closed between day 24 and 28.

57
Q

what causes spinal bifida

A

improper closing of the neural pores

58
Q

what acronym can be used to remember the derivisions of the the neural crest cells

A

CRESTCELL

59
Q

what do the neural crest cells derive into

A

C - chromaffin
R - rostral tissues
E - enteric nervous system
S - satellite and schwann cells
T - nervous tissue
C - carotid bodies
E - endocardial cushions
L - ligh skin/dark skin ie melanocytes
L - leptomeninges

60
Q

where are chromaffin cells found

A

the adrenal medulla

61
Q

what are the rostral tissues

A

all the connective tissue, bone and muscle of the head and neck

62
Q

what are the neural tissues formed from neural crest cells

A

spinal nerves and ganglia

63
Q

what are carotid bodies important for

A

measuring concentration of oxygen and carbon dioxide

64
Q

what are the leptomeninges of the brain

A

pia mater and arachnoid mater

65
Q

what does the surface ectoderm become

A

epithelial tissue like epidermis, nails, hair, sweat glands, oral cavity and ear canal

66
Q

what does the ectoderm become

A
  • neural tube, neural crest cells, cranial nerve ganglia
  • olfactory epithelium
  • lens of the eye
  • inner ear
67
Q

what is the inner ear important for

A

hearing and balance

68
Q

what is the lens of the eye important for

A

near and long vision by changing shape to refract the light differently

69
Q

what is the olfactory epithelium

A

the epithelial lining of the roof of the nasal cavity

70
Q

what acronym can be used to remember the derivisions of the ectoderm

A

ECTODERM

71
Q

breakdown the ECTODERM acronym

A

E - epithelial tissue
C - central nervous system
T - the lens
O - olfactory epithelium and the lens
D - damn crest cells
E - eyes - the retina
R - anterior pituitary gland
M - melatonin from the pineal gland

72
Q

what triggers the specialisation of the mesoderm

A

the notochord

73
Q

what does the notochord release to trigger the specialisation of the mesoderm

A

growth factors and sonic the hedgehog hormone

74
Q

what does the mesoderm specialise into

A
  • paroxial mesoderm
  • intermediate mesoderm
  • lateral plate mesoderm
75
Q

describe the development of the paroxial mesoderm

A

develops a cavity in the centre to form segments called somites, which form a cavity of their own called somatocoelie which extends to break the somites into the dermatomyotome and the sclerotome

76
Q

what does the dermatomyotome develop into

A

the dermatome and the myotome

77
Q

what does the dermatome do

A

it migrates and surrounds the neural tube to form the spinal meninges, dermis and subcutaneous tissue

78
Q

what does the myotome do

A

makes skeletal muscle of the trunk, back and limbs

79
Q

what does the sclerotome develop into

A

the vertebrae, intervertebral discs and the ribs

80
Q

what does the intermediate mesoderm develop into

A
  • renal system and ureters
  • gonads
81
Q

what does the lateral plate mesoderm divide into

A

somatic and splanchnic layers

82
Q

what does the somatic lateral plate do

A

makes the parietal layer of the body cavities

83
Q

what does the visceral lateral plate do

A

make the visceral layer of the body cavities

84
Q

name the derivisions of the splanchnic layer of the lateral plate mesoderm

A
  • adrenal cortex
  • lymph nodes
  • spleen
  • smooth muscle of the GIT
  • CVS
  • myeloid stem cells
  • lymphoid stem cells
  • erthyroid stem cells
85
Q

name the derivisions of the somatic layer of the lateral plate mesoderm

A

sternum
cartilage and bone of the limbs

86
Q

what are the areas of the sternum

A

the menubrium
xyphoid process
body

87
Q

what does the endoderm form

A

the gut tube, which is connected to the yolk sac and has three regions.

88
Q

what are the regions of the gut tube

A

foregut midgut hindgut

89
Q

what forms the gut tube

A

craniocaudal folding of the endoderm

90
Q

which region of the gut tube is the cranial portion

A

the foregut

91
Q

what do the endodermal cells of the gut tube collect and form

A

buds that form accessory organs to the GIT

92
Q

what does the first bud of the gut tube form

A

respiratory tract

93
Q

what does the second bud of the gut tube form

A

hepatic - liver and gall bladder

94
Q

what does the third bud of the gut tube form

A

the pancreas

95
Q

what does the foregut form

A
  • pharynx
  • oesophagus
  • stomach
  • first two parts of the duodenum
96
Q

what does the midgut form

A
  • the second two parts of the duodenum
  • jujenum
  • ileum
  • caecum
  • ascending colon
  • proximal two thirds of the transverse colon
97
Q

what does the pectinate line divide

A

the anal canal into ectoderm derived portion and endoderm derived portion

98
Q

which section of the anal canal is derived from the ectoderm

A

the third below the pectinate line

99
Q

what does the hindgut develop into

A
  • distal third of the transverse colon
  • descending colon
  • sigmoid colon
  • rectum and anal canal
100
Q

what does the buccopharyngeal membrane of the trilaminar disc develop into

A

the primitive pharynx, which forms the pharyngeal apparatus

101
Q

what forms from the pharyngeal apparatus

A

four pouches

102
Q

what does the first pouch of the pharyngeal apparatus form

A

the middle ear and the eustachian tube

103
Q

what does the second pouch of the pharyngeal apparatus form

A

the tonsils

104
Q

what does the third and fourth pouch of the pharyngeal apparatus form

A

the superior and inferior parathyroid glands, and the parafollicular cells

105
Q

what does the cloacal membrane of the trilaminar disc break down to form

A

the anal canal and the urethra