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Flashcards in Fertilization and early development Deck (145):
1

Capacitation-

involves change in the sperm plasma membrane (glycoprotein and lipid content changes) resulting in increased fertilizability

2

involves change in the sperm plasma membrane (glycoprotein and lipid content changes) resulting in increased fertilizability

Capacitation

3

Zona pellucida-

Surrounds oocyte; composed of sulfated glycoproteins ZP-1,2, and 3. ZP-2 and ZP-3 form long extracellular filaments that are cross linked by ZP-1.

4

surrounds oocyte; composed of sulfated glycoproteins ZP-1,2, and 3. ZP-2 and ZP-3 form long extracellular filaments that are cross linked by ZP-1.

Zona pellucida

5

ZP-3-

sulfated glycoprotein of the zona pellucida that acts a sperm binding receptor. Binding activated sperm plasma membrane H+ and Na+ transporters as well as Ca2+ transporter increasing sperm cytosolic pH and causing influx of Ca++ which triggers exocytosis of the acrosome

6

sulfated glycoprotein of the zona pellucida that acts a sperm binding receptor. Binding activated sperm plasma membrane H+ and Na+ transporters as well as Ca2+ transporter increasing sperm cytosolic pH and causing influx of Ca++ which triggers exocytosis of the acrosome

ZP-3

7

Acrosomal reaction-

sperm binds to ZP-3 sulfated glycoprotein of the zona pellucida, H+, Na+, and Ca++ transporters are activated causing exocytosis of the acrosome releasing it’s contents into the oocyte.

8

sperm binds to ZP-3 sulfated glycoprotein of the zona pellucida, H+, Na+, and Ca++ transporters are activated causing exocytosis of the acrosome releasing it’s contents into the oocyte.

Acrosomal reaction

9

Izumo-

sperm protein associated with sperm egg plasma membrane fusion

10

sperm protein associated with sperm egg plasma membrane fusion

Izumo

11

CD-9-

egg protein associated with sperm/egg plasma membrane fusion

12

egg protein associated with sperm/egg plasma membrane fusion

CD-9

13

Zona reaction-

Cortical granule exocytosis- Ca++ released from egg ER by IP3 from sperm/egg plasma membrane fusion causes release of granule contents to extracellular space which inhibits the ability of ZP-3 to bind with sperm and “hardens” the zona preventing polyspermy

14

Cortical granule exocytosis- Ca++ released from egg ER by IP3 from sperm/egg plasma membrane fusion causes release of granule contents to extracellular space which inhibits the ability of ZP-3 to bind with sperm and “hardens” the zona preventing polyspermy

Zona reaction

15

Aside from preventing polyspermy, what is another important result of Ca++ increase after fusion-

the egg chromosomes which have been arrested in metaphase 2, continue dividing with the destruction of CSF and activation of APCs. This creates the pro-nucleus of the egg (other half of DNA is exocytosed). Pro-nucleus of sperm is also created and both pro-nuclei enter S phase in preparation for first cleavage division. The pro-nuclei are pushed together by microfilaments and microtubules to for metaphase plate and new unique individual is formed. This is the culmination of fertilization.

16

oligospermia:

reduced numbers of sperm

17

asthenospermia:

reduced motility of sperm

18

teratozoospermia:

altered sperm morphology

19

Cleavage-

a series of mitotic cell divisions that occur as the embryo moves down the oviduct toward the uterus. (week one)

20

Blastomeres-

~16 sphereical cells comprising the embryo around day four or five which terms the embryo a morula

21

~16 sphereical cells comprising the embryo around day four or five which terms the embryo a morula

Blastomeres

22

Morula-

stage of embryo when it is comprised of ~16 spherical cells

23

stage of embryo when it is comprised of ~16 spherical cells

Morula

24

Compaction-

a change in the way blastomeres of the morula interact with eachother. Tight and gap junctions form and cells flatten together to form a ball. Cadherins play an important role here. Also embryo becomes more polarized to for distinct apical and basal surfaces and blastocoel forms. Embyo is now called a blastocyst

25

a change in the way blastomeres of the morula interact with eachother. Tight and gap junctions form and cells flatten together to form a ball. Cadherins play an important role here. Also embryo becomes more polarized to for distinct apical and basal surfaces and blastocoel forms. Embyo is now called a blastocyst

Compaction

26

Blastocyst-

the embyo after blastocoel has formed during compaction.

27

the embyo after blastocoel has formed during compaction.

Blastocyst

28

Hatching-

at the 6-7 day mark, the blastocoel reaches the uterus and get ready to implant by shedding the zona pellucida by realizing hydrolytic enzymes.

29

at the 6-7 day mark, the blastocoel reaches the uterus and get ready to implant by shedding the zona pellucida by realizing hydrolytic enzymes.

Hatching

30

Trophoblast-

the outer cells of the embryo that go on to form the placenta

31

the outer cells of the embryo that go on to form the placenta

Trophoblast

32

Syncytiotrophoblast-

formed by the fusion of a portion of the embryonic trophoblast with the epithelial cells of the uterine endometrium. Invades the uterine stroma and contacts maternal circulatory system which begins to nourish the embryo

33

formed by the fusion of a portion of the embryonic trophoblast with the epithelial cells of the uterine endometrium. Invades the uterine stroma and contacts maternal circulatory system which begins to nourish the embryo

Syncytiotrophoblast

34

Cytotrophoblasts-

trophoblast cells that do not fuse with the endometrium and divide via mitosis to add cells to the rapidly proliferating syncytiotrophoblast

35

trophoblast cells that do not fuse with the endometrium and divide via mitosis to add cells to the rapidly proliferating syncytiotrophoblast

cytotrophoblast

36

Ectopic implantation-

abnormal site of implantation

37

Human chorionic gonadotropin-

(HCG) secreted by the syncytiotrophoblast to maternal blood stream causing maternal release of estrogen and progesterone to prevent the sloughing of the endometrium and allow maintenance of the pregnancy

38

(HCG) secreted by the syncytiotrophoblast to maternal blood stream causing maternal release of estrogen and progesterone to prevent the sloughing of the endometrium and allow maintenance of the pregnancy

Human chorinic gonadotropin

39

Decidual reaction-

trigger by the invasion of the syncytiotrophoblast into the endometrium. Endometrial cells surrounding the embryo begin to accumulate glycogen and lipids.

40

trigger by the invasion of the syncytiotrophoblast into the endometrium. Endometrial cells surrounding the embryo begin to accumulate glycogen and lipids.

Decidual reaction

41

Decidual cells-

created from endometrial cells that stock up on lipid and glycogen after invasion of syncytiotrophoblasts. They surround the embryo to form the decidua.

42

created from endometrial cells that stock up on lipid and glycogen after invasion of syncytiotrophoblasts. They surround the embryo to form the decidua.

Decidual cells

43

Decidua-

decidual cells surrounding the embryo. One function may be to protect the embryo from the maternal immune system.

44

Bilaminar disc-

flattening of the inner cell mass to form two layers, the epiblast and the hypoblast. The hypoblast is away from the site of fusion and cells are cuboidal, epiblast is adjacent to the site of fusion and newly forming amniotic sac and cells are columnar

45

flattening of the inner cell mass to form two layers, the epiblast and the hypoblast. The hypoblast is away from the site of fusion and cells are cuboidal, epiblast is adjacent to the site of fusion and newly forming amniotic sac and cells are columnar

Bilaminar disc

46

Animal pole-

the inner cell mass, as opposed to the trophoblast

47

Amniotic cavity-

fluid space between the inner cell mass and adjacent trophectoderm

48

fluid space between the inner cell mass and adjacent trophectoderm

amniotic cavity

49

Epiblast-

layer of bilaminar disc adjacent to the amniotic cavity; will eventually give rise to the embryo as well as extraembryonic structures. Identifies the dorsal section of the embryo

50

layer of bilaminar disc adjacent to the amniotic cavity; will eventually give rise to the embryo as well as extraembryonic structures. Identifies the dorsal section of the embryo.

Epiblast

51

Hypoblast-

layer of the bilaminar disc that is not adjacent to the amniotic cavity and will only give rise to extraembryonic structures; ie. Yolk sac. Identifies the ventral aspect of the embryo.

52

Extraembryonic mesoderm-

cells that break free of the primary yolk sac (around day 9) and fill the space between the embryo and the trophoblast. A dense cluster of these cells will give rise to the umbilical chord.

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cells that break free of the primary yolk sac (around day 9) and fill the space between the embryo and the trophoblast. A dense cluster of these cells will give rise to the umbilical chord.

Extraembryonic mesoderm

54

layer of the bilaminar disc that is not adjacent to the amniotic cavity and will only give rise to extraembryonic structures; ie. Yolk sac. Identifies the ventral aspect of the embryo.

Hypoderm

55

Gastrulation-

mass migration of cells to form three germ layers; ectoderm, endoderm, mesoderm. All are derived from the epiblast.

56

mass migration of cells to form three germ layers; ectoderm, endoderm, mesoderm. All are derived from the epiblast.

Gastrulation

57

Primitive streak-

thickening of epiblastic cells to demarcate the left/right and anterio/posterior axis of the embryo

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thickening of epiblastic cells to demarcate the left/right and anterio/posterior axis of the embryo

Primitive streak

59

Mesoderm-

formed by migration of the epiblastic cells through the primitive streak, they displace hypobalstic cells and become the middle layer of the embryo at this point

60

formed by migration of the epiblastic cells through the primitive streak, they displace hypobalstic cells and become the middle layer of the embryo at this point

Mesoderm

61

Endoderm-

cells that migrate through the primitive streak and displace hypoblastic cells forming the bottom (ventral) aspect of the embryo

62

cells that migrate through the primitive streak and displace hypoblastic cells forming the bottom (ventral) aspect of the embryo

Endoderm

63

Ingression-

the migration of epiblastic cells through the primitive streak to form mesoderm and endoderm

64

the migration of epiblastic cells through the primitive streak to form mesoderm and endoderm

Ingression

65

Notochord-

the rostral most epiblastic cells that migrate through the primitive node (Hensen’s node) forming a thick cord that will provide important structural support for the embryo as well as playing a key role in cell differention signaling and the development of the nervous system. The vertebral column eventually forms around the notochord

66

the rostral most epiblastic cells that migrate through the primitive node (Hensen’s node) forming a thick cord that will provide important structural support for the embryo as well as playing a key role in cell differention signaling and the development of the nervous system. The vertebral column eventually forms around this:

Notochord

67

Neurulation-

formation of the nervous system, begins 3rd week

68

formation of the nervous system, begins 3rd week

Neurulation

69

Neural tube formation-

ectoderm cells directly dorsal to the notochord are induced by the notochord to form the neural plate

70

ectoderm cells directly dorsal to the notochord are induced by the notochord to form the neural plate

Neural tube formation

71

Neural plate-

thickening of the ectoderm directly overlying the notochord

72

Neural folds-

buckling of the neural plate, ~day 18. Neural folds at the cranial end of the notochord enlarge and will eventually become the brain.

73

buckling of the neural plate, ~day 18; the ones at the cranial end of the notochord enlarge and will eventually become the brain.

Neural folds

74

Neural tube-

end of the third week; formed by neural folds folding around and fusing to completely enclose the neural tube in ectoderm

75

end of the third week; formed by neural folds folding around and fusing to completely enclose this structure in ectoderm

Neural tube

76

Neural crest cells-

population of cells at the lateral border of the neural folds that migrate away from the neural tube to form spinal and autonomic ganglia, Schwann’s cells, the meninges, the adrenal medulla, and melanocytes. Sometimes called the “4th germ layer”.

77

population of cells at the lateral border of the neural folds that migrate away from the neural tube to form spinal and autonomic ganglia, Schwann’s cells, the meninges, the adrenal medulla, and melanocytes. Sometimes called the “4th germ layer”.

Neural crest cells

78

Paraxial mesoderm-

one of three types of mesodermal swellings around the third week eventually become 42-44 pairs of somites present around 5th week; become axial skeletal and musculature and associated dermis of the skin

79

one of three types of mesodermal swellings around the third week eventually become 42-44 pairs of somites present around 5th week; become axial skeletal and musculature and associated dermis of the skin

Paraxial mesoderm

80

Intermediate mesoderm-

forms two long swellings running rostral-caudal on both sides of the notochord; will become urogenital system

81

forms two long swellings running rostral-caudal on both sides of the notochord; will become urogenital system

Intermediate mesoderm

82

Lateral mesoderm-

begins to display fluid spaces that separate the lateral mesoderm into dorsal and ventral wings. The dorsal wing called the somatic mesoderm will help form the lateral and ventral body wall, while the ventral wing called the splanchnic mesoderm will form the gut lining and form mesentery

83

begins to display fluid spaces that separate the lateral mesoderm into dorsal and ventral wings. The dorsal wing called the somatic mesoderm will help form the lateral and ventral body wall, while the ventral wing called the splanchnic mesoderm will form the gut lining and form mesentery

Lateral mesoderm

84

Somatic mesoderm-

dorsal wing of the lateral mesoderm; will form lateral and ventral body wall

85

dorsal wing of the lateral mesoderm; will form lateral and ventral body wall

somatic mesoderm

86

Splanchnic mesoderm-

ventral wing of the lateral mesoderm will surround the gut and form mesentery

87

ventral wing of the lateral mesoderm will surround the gut and form mesentery

Splanchnic mesoderm

88

Coelom-

the space that splits the lateral mesoderm

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the space that splits the lateral mesoderm

Coelom

90

Angiogenesis-

formation of blood vessels (3rd week) in extraembryonic locations, specifically the yolk sac, extraembryonic mesoderm, the connecting stalk, and the chorion. Heart tubes also begin to develop in the embryonic mesoderm cranial to the neural plate at this time; embryonic vessel development progresses so circulation begins at the end of the 3rd week

91

formation of blood vessels (3rd week) in extraembryonic locations, specifically the yolk sac, extraembryonic mesoderm, the connecting stalk, and the chorion. Heart tubes also begin to develop in the embryonic mesoderm cranial to the neural plate at this time; embryonic vessel development progresses so circulation begins at the end of the 3rd week

Angiogenesis

92

Embryo folding-

4th week. Embyo begins to fold along two axes; longitudinal and transverse. Gives rise to basic body plan by: 1) converting three flat germ layers into cylindrical endoderm (central/inside), mesoderm (medial) and ectoderm (peripheral/outside) 2) seals off intraemryonic coelom from extraembyonic coelom and 3) rolls endoderm into tubular gut surrounded by mesentery and forms ventral wall

93

4th week. Embyo begins to fold along two axes; longitudinal and transverse. Gives rise to basic body plan by: 1) converting three flat germ layers into cylindrical endoderm (central/inside), mesoderm (medial) and ectoderm (peripheral/outside) 2) seals off intraemryonic coelom from extraembyonic coelom and 3) rolls endoderm into tubular gut surrounded by mesentery and forms ventral wall

Embryo folding

94

ECTODERM derivatives:

Epidermis, hair, nails, cutaneous and mammary glands; central and peripheral nervous system

95

Epidermis, hair, nails, cutaneous and mammary glands; central and peripheral nervous system

ECTODERM derivatives

96

MESODERM derivatives:

Paraxial: Muscles of head, trunk, limbs, axial skeleton, dermis, connective tissue; Intermediate: Urogenital system, including gonads; Lateral: Serous membranes of pleura, pericardium, and peritoneum, connective tissue and muscle of viscera, heart, blood cells

97

Paraxial: Muscles of head, trunk, limbs, axial skeleton, dermis, connective tissue; Intermediate: Urogenital system, including gonads; Lateral: Serous membranes of pleura, pericardium, and peritoneum, connective tissue and muscle of viscera, heart, blood cells

Mesoderm derivatives

98

ENDODERM derivatives:

Epithelium of lung, bladder and gastrointestinal tract; glands associated with G.I. tract, including liver and pancreas.

99

Epithelium of lung, bladder and gastrointestinal tract; glands associated with G.I. tract, including liver and pancreas.

Endoderm derivates

100

blastomeres initially have similar development potencies, each capable of giving rise to a complete embryo (vs mosaic development). Development largely depends on induction.

Regulative development-

101

cell fate is already assigned during cleavage and a strict development plan is in place whereby removal of one or more cells results in an incomplete embryo (not present in humans)

Mosaic development-

102

the ability of one cell (or some type of signal) to influence the development of another cell. Leads to regulative pattern of development.

Induction-

103

The first “decision” for an embryonic cell:

Inner cell mass or trophoblast. Regulated by the Hippo signaling pathway. Hippo signaling phosphorylates Yap and also inhibits Tead4 in inner cells. Hippo is inhibited in outer cells stimulating trophoblast formation where Yap and Tead4 are active.

104

Yap-

associated with trophoblast development

105

Tead4-

associated with trophoblast development

106

Second “decision” for inner embryonic cells:

Epiblast or hypoblast. Oct4, Nanog, and Sox2 push cells toward epiblast. Gata positive cells form hypoblast.

107

Oct 4 -

pushes cells toward epiblast

108

Nanog-

push cells toward epiblast

109

Sox2-

push cells towards epiblast

110

Gata-

push cells towards hypoblast

111

Third “decision” for inner embryoninc cells-

Ectoderm, endoderm, or Mesoderm. High Oct 4/ low BMP4→ embryonic stem cell self renewal.
High Oct 4/ high BMP4→ mesoderm
Low Oct4/ High BMP4 → ectoderm
Low Oct4/ Low BMP4 → neuroectoderm
Nanog expression inhibits neuroectoderm and neural crest fates

112

bone morphogenic protein 4. Regulates cell differentiation between ectoderm and mesoderm fates

BMP 4-

113

fibroblast growth factor; pushes cells to ectoderm; inhibited by Activin, BMP, Wnt; later influence of BMP 4 leads to skin rather than neural

FGF-

114

lead to endoderm→ liver, lung, pancreas

Activin and Nodal-

115

can give rise to all embryonic and extra-embryonic cell types and structures

Totipotent-

116

can give rise to all embryonic cell types and structures

Pluripotent-

117

can give rise to multiple (but not all) cell types

Multipotent-

118

can give rise to just one type of cell

Unipotent-

119

EGA; 4-8 cell stage, most maternal mRNA has been degraded, ~day 3

Embryonic genome activation-

120

signals that alter cell fate

Morphogens-

121

cells producing morphogens

Inducers-

122

induction involving diffusible molecules

Paracrine-

123

involves cell-cell contact

Juxtacrine-

124

cells stimulate themselves

Autocrine-

125

Factor regulating dorsal/ventral axis development-

Sonic hedgehog

126

Factor regulating left/right asymmetrical axis-

ciliary cells of the primitive node direct Nodal to the left side of the body, Nodal stimulates Lefty which is not strong enough to inhibit Nodal on the left but inhibits whatever Nodal is present on the right

127

activated by Nodal, it inhibits low amounts of Nodal on the right side

Lefty-

128

Nodal-

accumulates on the left due to ciliated cells of the primitive node waving the same direction, it activates Lefty which inhibits leftover Nodal present on the right side

129

responsible for regulating development of anterior/posterior axis (careful, this is cranial/caudal axis in humans)

Hox genes-

130

in the primitive node, longer exposure to this gives cells a posterior/caudal fate:

Retinoic acid-

131

The “Big 5” signaling pathways involved in development:


1. TGF (transforming growth factor); includes TGF beta, BMP, Activin, Nodal
2. Hedgehog
3. FGF (fibroblast growth factor)
4. Wnt
5. Notch

132

caused by defective Hedgehog signaling

Cyclopia-

133

mutaions in FGFR3

Achondroplasia and dwarfism-

134

can promote cancer-especially in the epithelial cells of the colon

Hyperactivity of Wnt-

135

dispruption of the Notch pathway caused by mutation of Jagged1 gene

Alagille syndrome-

136

epithelial mesenchymal; TGF-beta, FGF, Wnt, and Notch pathways; important in cell adhesion and migration, regulated by transcription factor Snail

EMT-

137

mesenchymal epithelial; BMP pathway

MET-

138

transcription factor regulationg motility and adhesion, represses cadherin, claudin, and occluding resulting in loss of tight junctions and adherins

Snail-

139

Two drivers of epithelial folding-

cell proliferation and contraction of actin in zonula adherins

140

Two essential features of stem cells-

1. Not terminally differentiated but can give rise to daughter cells that terminally differentiate 2. Can self-renew

141

rise from stem cells, they are in transit between stem cells and terminally differentiated cells, this is how stem cells are conserved while amplifying their daughter cell numbers. Mitotically active. Can only divide a finite number of times, unlike stem cells.

Progenitor cells-

142

How are cells “locked in” to a particular pattern of gene expression?

Epigenetic changes involving gene silencing via methylation

143

when epigenetic changes are “wiped clean” . Ex: imprinting?.

Epigenetic reprogramming-

144

Two ways stem cell health is maintained:

1. The use of progenitor cells 2. Retention of parent DNA strand (less likely to incur mutations)

145

Inhibitors of DNA binding proteins. They prevent premature differentiation of stem cells. Disfunction can lead to tumorigenesis

Id proteins-