Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BRS 1b > 11.2 Early Foetal Development > Flashcards

11.2 Early Foetal Development Flashcards

1
Q

What does the endoderm develop into?

A

GI tract, liver, pancreas, lung, thyroid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does the embryogenic stage involve?

A
  • establishing the early embryo from the fertilised oocyte
  • determination of of two populations of cells: pluripotent embryonic cells (contribute to the foetus), extraembryonic cells (contribute to the support structures e.g. placenta)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is fertilsation (conceptual) age measured?

A

measured from the time of fertilisation (assumed to be +1 day from last ovulation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why can fertilsation age be difficult to measure?

A

Difficult to know time of fertilisation exactly because could happen days after intercourse, unless IVF where fertilisation occurs in a dish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How is gestational age measured?

A

calculated from time of the beginning of the last menstrual period (LMP)
Determined by fertilsation date (+14 days), if known, or early obstetric ultrasound and comparison to embryo size charts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is carnige staging?

A

Method of tracking embryoloical development.
Allows comparison of developmental rates between species.
Covers the window of 0-60 days fertilisation age in human.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is carnigie staging measured?

A

23 stages of embryo development based on embryological features not time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are 3 ways of measuring embryo-foetal development?

A

fertilisation age
gestational age
carnigie stage (only until 60 days fertilisation age)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the three stages of of embryo-foetal development?

A
  1. Embryogenic Stage
  2. Embryonic Stage
  3. Foetal Stage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When does the embryogenic stage occur?

A

14-16 days post fertilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When does the embryonic stage occur?

A

16-50 days post fertilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When does the foetal stage occur?

A

50-270 days post fertilisation ( 8 -38 weeks or 10-40 weeks gestational age)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

In which trimester does the embryogenic stage occur?

A

first

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In which trimester does the embryonic stage occur?

A

first

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In which trimester does the foetal stage occur?

A

second and third trimester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does the embryonic stage involve?

A
  • establishment of the germ layers and differentiation of tissue types
  • establishment of the body plan
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the foetal stage involve?

A
  • major organ systems now present (although not all organs will be in the position they will be in at birth)
  • migration of some organ systems to final location
  • extensive growth and acquisition of foetal viability (survival outside the womb)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the difference between an oocyte and a zygote?

A

Both one cell
Oocyte - unfertilised egg
Zygote - fertilised cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 2-8 cell embryos known as and why?

A

cleavage stage embryos

mitotic divisions the cells undergo to go from zygote to 8 cell embryo are known as cleavage divisions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the 16+ cell embryo known as ?

A

Morula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What proceeds the morula and how many cells is it roughly?

A

blastocyst

200-300 cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where does the development of the zygote into the blastocyst occur?

A

along the fallopian tube and into the uterus where it implants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

When does the maternal to zygotic transition occur?

A

4-8 cell stage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens in the maternal to zygotic transition? (3)

A
  • transcription of embryonic genes (zygotic genome activation)
  • increased protein synthesis
  • organelle maturation (mitochondria, golgi)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

When does compaction occur?

A

Around 8 cell stage or later

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What occurs during compaction?

A

Outer cells become pressed against zona, and change from spherical to wedge shaped.
Outer cells connect to each other through tight gap junction and desmosomes
Forms barrier to diffusion between inner and outer embryo.
Outer becomes polarised with distinct apical and basal polarity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the two distinct cell types in embryo after compaction?

A

inner and outer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What’s the difference in embryological structure between the morula and the blastocyst?

A

Outer cells remain the same (tight ring around internal edge of zona) forming shell.
Inner cells reorganise into clump at one end of the blastocyst, forming blastocoel cavity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the embryo contained in throughout zygote to blastocyst stages?

A

Zona pellucida

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the zona pellucida and what does it do?

A

hard protein shell

inhibits polyspermy and protects early embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What does the inner cell mass of the blastocyst give rise to?

A

Pluripotent embryonic cells that will contribute to the final organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the outer ring of cells (which develops during the morula phase) known as in the blastocyst?

A

trophectoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How is the trophoectoderm formed?

A

Compaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What does the trophectoderm give rise to?

A

extra-embryonic cells that contribute to the extraembryonic structures that support development

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How is the blastocoel formed?

A

Formed osmotically
Trophoblasts (trophectoderm cells) pump Na+ ions into cavity
Water then follows osmotically to create fluid filled cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

When is does hatching occur?

A

Day 5-6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Why does hatching occur?

A

After blastocyst stage, developmental potential becomes limited as contained within zona. The blastocyst must also hatch to implant in the uterine wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Why does hatching occur?

A

After blastocyst stage, developmental potential becomes limited as contained within zona. The blastocyst must also hatch to implant in the uterine wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is hatching?

A

Escape of the blastocyst from the zona pellucida

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How does hatching occur?

A 
enzymatic digestion (blastocyst secrete enzymes)
cellular contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What two types of cells do the trophectoderm cells develop into?

A

Syncitiotrophoblasts

Cytotrophoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What in the function of the syncitiotrophoblasts?

A

Invade maternal endometrium and destroys local cells (including capillaries, which allow the syncitiotrophoblasts to be bathed in maternal blood)
Creates interface between embryo and maternal blood supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are the function of cytotrophoblasts?

A

Remain individual so they can continue to divide to provide cells for the syncytiotrophoblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What two components does the inner cell mass develop into?

A

epiblast

hypoblast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the epiblast?

A

cells from which the foetal tissues will be derived

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the hypoblast?

A

cells which will form the yolk sac (extraembryonic structure)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Where does the hypoblast lie?

A

cytotrophoblasts
epiblast
hypoblast
blastocoel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What important development occurs in the embryo around day 12?

A

bi-laminar embryonic disc formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Why is the bi laminar (two-layer) embryonic disc important?

A

because it is the final stage before gastrulation

50
Q

What does the bilaminar embryonic disc consist of?

A

epiblasts (on top)

hypoblasts

51
Q

What happens during the bi-laminar disc formation?

A

Epiblast cells separate into two layers and a new cavity is formed - the amniotic cavity.

52
Q

What is the name of the epiblast cells above the amniotic cavity?

A

amnion cells

53
Q

What two structures is the bi laminar embryonic disc in between?

A

amniotic cavity
bi-laminar embryonic disk
blastocoel

54
Q

What do the amnion cells give rise to?

A

extra-embryonic membranes

55
Q

What does the syncitiotrophoblast secrete?

A

hCG (beta hCG subunit in blood and urine is how pregnancy detected)

56
Q

the genes of the embryo are not transcribed until..

A

the maternal to zygotic transition

57
Q

How does the embryo get through the first divisions (day 0-4)?

A

Embryo is dependent on maternal mRNAs and proteins to get through the first divisions.

58
Q

Where does the mRNA and proteins required for the first divisions from?

A

mRNA and proteins are synthesised and stored during oocyte development (pre-ovulation).

failure to synthesise, store or interpret these mRNAs and proteins during oogenesis can impair embryonic development.

59
Q

What are the three germ layers?

A

endoderm
ectoderm
mesoderm

60
Q

When does the primitive streak form?

A

Day 15

61
Q

What does the formation of the primitive streak define?

A

The major body axis of the embryo

62
Q

What is the primitive streak

A

A thickened structure along the midline of the epiblast near the caudal end of the bilaminar disc.

63
Q

What does the endoderm develop into?

A 
GI tract
liver
pancreas
lung
thryoid
64
Q

What is gastrulation?

A

The process whereby the bilaminar embryonic disc undergoes reorganisation to form a trilaminar disc

65
Q

What does the ectoderm develop into?

A

CNS and neural crest
Skin epithelial
Tooth enamel

66
Q

What does the mesoderm develop into?

A

blood (endothelial cells, RBC, WBC)
muscle (smooth, skeletal, cardiac)
gonads, kidneys, adrenal cortex
bone, cartilage

67
Q

When does notochord formation occur?

A

day ~13+

68
Q

What is the notochord?

A

rod like tube structure formed of cartilage-like cells

69
Q

Where does the notochord form?

A

forms along the embryo midline, under the ectoctoderm

forms from the primitive streak and grows toward the head end of the embryo

70
Q

How does the notochord organise the development of the neural system?

A

Through control of the neural plate (area of thickened ectoderm)

71
Q

What is the role of the notochord?

A

acts as a key organising centre for development

releases signals for neurulation (CNS formation) and mesoderm development

72
Q

When does the neural tube close at the head end?

A

d23

73
Q

When does the neural tube close at the tail end?

A

d27

74
Q

What does closure of the neural tube at the head end precede?

A

formation of brain structures

75
Q

What are 2 developmental defects that result from failure of neural tube closure?

A

anencephaly

spina bifida

76
Q

What is anencephaly?

A

absence of most of the skull and brain;

arises from failure to close at the head end

77
Q

What is spina bifida?

A

open neural tube at birth, usually lower spine due to failure to close tail end;
varying severity

78
Q

How can we classify neural crest cells?

A

According to where the end up in the embryo

79
Q

What is somitogenesis?

A

formation of somites

80
Q

What are somites?

A

somites arise from paired blocks of paraxial mesoderm flanking the neural tube and notochord which bud off

81
Q

Where does somitogenesis begin?

A

At the head end of the embryo and progresses down the long axis of the embryo

82
Q

What two types of embryonic tissue are somites made of?

A

sclerotome

dermomyotome

83
Q

What is scerotome?

A

vertebrae and rib cartilage

84
Q

What does dermomyotome sub divide into?

A

Dermatome: gives rise to dermis of skin, some fat, connective tissues of neck and trunk
Myotome: forms the muscles of the embryo

85
Q

When does formation of the gut tube occur?

A

day 16

86
Q

The primitive gut arises from what two types of folding in the embryo?

A

ventral folding

lateral folding

87
Q

What is ventral folding?

A

where the head and tail ends curl together

88
Q

What is lateral folding?

A

where the two sides of the embryo roll

89
Q

How does the primitive gut arise?

A

two types of folding occur in the embryo, pinching off the yolk sac and this forms the primitive gut

90
Q

What three structures does the primitive gut develop into?

A

foregut
midgut
hindgut

91
Q

What does the foregut develop into?

A 
oesauphagus
stomach
upper duodenum
liver 
gallbladder
92
Q

What does the midgut develop into?

A

lower duodenum
remainder of small intestine (ilium, jejunum)
ascending and transverse colon

93
Q

What does the hindgut develop into?

A

last third of transverse colon
descending colon
rectum and upper anal canal

94
Q

How do the lungs develop?

A

In the 4th week

  • arises from the lung bud, and endoderm structure adjacent to the foregut
  • lung bud splits in two
  • -> then progressively branches through development
95
Q

How does the heart develop?

A

Day 19: begins as tube of mesoderm
Day 22: beating and pumping blood
4 weeks: fetal heartbeat detectable (6 weeks gestational age)

96
Q

How do gonads develop?

A

forms from mesoderm as bipotential (i.e. not committed to testis or ovaries) structures known as gonadal ridges

97
Q

How do gonads develop in XY embryos?

A

presence of SRY gene on Y chromosome directs gonadal cells to become Sertoli cells, triggering testis development, Leydig cell formation and testosterone production

98
Q

How do gonads develop in XX embryos?

A

absence of SRY leads to gonadal cells adopting a granulosa cell fate and ovary development, requires reinforcement by FOXL2

99
Q

What are the two ends of the embryo?

A 
Cranial end
Caudal end (tail)
100
Q

At the cranial end of the embryonic disk, the primitive streak expands to create a…

A

primitive node (which contains primitive pit)

101
Q

The primitive node and primitive pit form the …

A

primitive groove

102
Q

Cells migrate inwards towards the primitive groove and slip beneath it in a process known as…

A

invagination

103
Q

Hypoblast cells are displaced by cells invaginating and a new proximal cell layer is formed called the..

A

Definitive endoderm

104
Q

After invagination what are the remaining epiblast cells called?

A

Ectoderm (most exterior, distal layer)

105
Q

Some of the invaginated epiblast cells remain in the space between the ectoderm and definitive endoderm, what happens to this layer?

A

These cells form a germ layer, the mesoderm

106
Q

What do the first cells to invaginate through the primitive groove form?

A

the definitive endoderm

107
Q

What do cells that invaginate but don’t form the definitive endoderm become?

A

Cells that remain in the space become the mesoderm

108
Q

The formation of the primitive streak defines which axis of the embryonic disc?

A

head-tail
AND
left-right

109
Q

What are the two functions of the notochord?

A

Form neural groove –> notochord signals direct the neural plate ectoderm to invaginate

Creates two ridges (neural folds) running along crainio-caudal axis

110
Q

What cells form in the neural crest?

A

neural crest cells

111
Q

How does the neural tube form?

A

neural folds move together over neural groove and fuse

112
Q

What control the process of neural tube formation?

A

notochord

113
Q

What are some features of neural crest cells?

A

endoderm derived

plastic and migrate extensively during developement

114
Q

What are 4 types of neural crest cells:

A

cranial
cardiac
trunk
vagral & sacral

115
Q

What do cranial neural crest cells form? (5)

A 
cranial neurones
glia
lower jaw
middle ear bones
facial cartilage
116
Q

What do cardiac neural crest cells form?

A

aortic arch
pulmonary artery septum
large artery walls

117
Q

What do trunk neural crest cells form? (5)

A 
dorsal root ganglia
sympathetic ganglia
adrenal medulla
aortic nerve clusters
melanocytes
118
Q

What do vagral and sacral neural crest cells form?

A

parasympathetic ganglia

enteric nervous system ganglia

119
Q

What do defects of neural crest migration/specification lead to?

A 
birth defects
including:
- pigmentations disorders
- deafness
- cardiac and facial defects
- failure to innervate the gut
120
Q

What is unique about the rate of budding off of somite pairs?

A

species specific as is number of pairs

human: 90 mins/pair, 44 pairs

BRS 1b (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions