[LE2] Lecture 9 Flashcards
(115 cards)
1
Q
Birds are from an __________ egg, which will then be separated into a group with no mammary glands
A
amniote
2
Q
In the amniote egg is where you will be having the four extra embryonic membrane, what are these four?
A
amnion, allantois, chorion, yolk sac
3
Q
Encloses the embryo so you will have an amniotic cavity where the embryo is floating
A
Amnion
4
Q
Area for excretion of waste of the animal
A
Allantois
5
Q
Protects the entire embryo, including the three extra embryonic membrane
A
Chorion
6
Q
Covers the __________ and source of food in avians
A
yolk sac
7
Q
REASON WHY BIRD IS USED AS EMBRYONIC MODEL:
A
- Easily obtained
- Controlled developmental stage needed by incubating when ready
- Relatively large embryo
- Good for surgical manipulation
- Many similarities to human development
- Inexpensive
8
Q
On day 2, you will see a big blastoderm forming, and this is where the _______________ will occur
A
meroblastic discoidal
cleavage
9
Q
TRUE OR FALSE:
Internal fertilization occurs in avian
A
TRUE
10
Q
A follicle will be ovulated, and once it has been ovulated, it will now go down to your _____________, then _____________ would be the area where fertilization occurs
A
infundibulum
11
Q
If fertilization would occur, your blastodisc will become a _____________
A
blastoderm
12
Q
If no fertilization will occur, such as in your layer chickens (these are the ones that provide us our table egg), they would still undergo the same ___________________
A
egg development
13
Q
In the magnum, you’ll be having your ___________
A
albumin
14
Q
In the isthmus, you’ll be having the ________________ added
A
shell membrane
15
Q
In ____________, where around 21-24 hours is going to be a store; this would be a time that your egg is going to stay longer
○ That is also the reason why in phylogenetic history, only the ______ side of the uterus of your birds remains because if two eggs would lodge at the same time at your vaginal junction, then the egg could be retained, causing the death of the cell
○ Only one side, because once your chicken starts to lay egg, they will be laying egg consequently ______________
A
uterus
left
every day (every 24 hours)
16
Q
What is the CLEAVAGE IN AVIANS?
A
Discoidal meroblastic cleavage
17
Q
Cleavage in avians is quite similar to your _________
A
zebrafish
18
Q
You would have hypoblast that would laminate from the epiblast, forming two cavities:
A
- Blastocoel
- Subgerminal cavity
19
Q
Separating the yolk from your embryonic development
a) Blastocoel
b) Subgerminal cavity
A
Subgerminal cavity
20
Q
1st cleavages occur in a small area of the cytoplasm called the __________
A
blastodisc
21
Q
These cells do not penetrate through the whole cell, so cells are __________ with each other
A
continuous
22
Q
As cleavage continues, a small disc of cells about 4 to 6 layers deep is created in the center of the ___________
A
blastoderm
23
Q
Underneath the blastodisc is a fluid-filled cavity called the ______________
A
subgerminal cavity
24
Q
In the center of the blastoderm, cells in the deeper layer die off, forming a single-celled layer of blastoderm called
________________
This will form the actual embryo. These cells are called __________
A
area pellucida
epiblast
25
On the margin of the blastodisc: Deeper cells do not die off, creating a thicker layer called _____________
area opaca
26
Area opaca will be separated into:
Area opaca vitellina
Area opaca vasculosa
27
Where blood vessels will develop and also the blood island (where the embryo will get its blood
Area opaca vasculosa
28
__________ (embryo proper and extra EMs - chorion, amnion, and allantois) and ___________ (yolk sac) form from the blastoderm
epiblast and hypoblast
29
Epiblast is more _______
Hypoblast is more ________
dorsal
ventral
30
2 mechanisms of FORMATION OF THE EPIBLAST AND HYPOBLAST:
○ Cells _____________ from the epiblast and migrate as islands into the subgerminal cavity (primary hypoblast)
○ Cells near the posterior end __________ as a sheet toward the anterior end (inside the subgerminal cavity) (secondary hypoblast or endoblast)
delaminate
migrate
31
Fomation of the Chick blastoderm:
● The area from hypoblast islands delaminates ventrally and from the _______________ forms your secondary hypoblast coming from your PMZ
● Now they would migrate to the anterior side, meeting your primary hypoblast and eventually closing off, and you will have ____________ and subgerminal cavity below
Koller's sickle
blastocoel
32
Avian embryos form a structure called the ______________, which is the thickening of the epiblast near the posterior end
primitive streak
33
Primitive streak:
- _____________ to the blastopore
- Defines the major __________ of the avian embryo
- This is where the formation of __________ begins
analogous
body axes
germ layer
34
As you have your blastocoel from Koller's sickle from the PMZ, you will be having your ______________
primitive streak
35
First movement of the primitive streak is anterior, going to the area pellucida, allowing the formation of _______________ and ______________
prechordal plate
head process
36
As the primitive streak extends, a depression forms at the midline called the _________________
○ Cells will migrate into the ____________
○ Analogous to the amphibian blastopore
primitive groove
blastocoel
37
Why is this analogous to blastopore:
Because this is the first opening of the embryo
38
Eventually, you would have a thin-like structure on top called ________________
Hensen's node
39
It would be bounded by primitive groove
and you would have primitive folds
Different from the area where you will be having your neurulation
Hensen's node/Primitive pit
40
At the anterior end, a thickening called ______________ is a funnel-shaped depression where cells begin to migrate by ingression into the blastocoel
Hensen's node
41
Analogous to the amphibian _____________ lip or fish _________ shield (organizer)
dorsal blastoporal
embryonic
42
Notice how it is similar that your organizer because hensen's node would allow the formation of dorsal structures such as ______________
notochord
43
HOW WAS THE HENSEN'S NODE DETERMINED TO BE THE AVIAN ORGANIZER?
1. Region whose cells become the __________________ and chordamesoderm
2. Region whose cells can both induce and pattern a second _______________ when transplanted
3. Expresses the same marker genes, such as the transcription factor _________
prechordal plate
embryonic axis
goosecoid
44
Hensen's node is determined to be an avian organizer because they did a move-it experiment
They got an area of the duck embryo with the hensen's node, transplanting it to the chicken embryo, and still it's capable of developing ______________
neural tube
45
_____________ is found within the area of Hensen's node
Notochord
46
In _______, which is a BMP induced signaling, which cannot be found in the area that would be respective neural tissue
Smad1
47
You have Hensen's node, and it ____________ and neutralizes the ectoderm, whereas your BMP7 makes your ectoderm epidermal
dorsalizes
48
MOLECULAR SIGNALS FOR MESODERM FORMATION AND NEURULATION:
[A] Fgf8 and nodal is being blocked by ____________
[B] Further, as they move forward, your fgf8 and Cerberus are being brought together by the movement of _______________
Cerberus
primitive streak
49
Fgf8 would have Tbx6 to specify the _____________ which will be your notochordal area
mesodermal
50
[C] ______ induces the formation of neural plate/neural tissues because notochord is needed to neuralize the ectoderm
Tbx6
51
[D] Further, the Churchill in the migrating neural tissues could induce _____ and block the primitive streak
Sip1
52
- That's why it prevents ___________ because what happens now you have reached the area where you would have your neural tissue that would already be formed
- By this time, all tissues and areas are formed that need to be ___________
- Primitive streak also reached its maximum length and moves ________
ingression
neuralize
caudal
53
Primitive streak elongate by ____________, they move forward, and some cells move back to the original streak
intercalation
54
- That would allow this Red area (left photo) that will be needed to form the entire primitive streak
- Once you have a primitive streak, the first one that it would produce is the _____________, then notochord induces the ___________ to form
notochord, neural ectoderm
55
And flanking the notochord will be your __________________, also known as segmental plate mesoderm, and you would have your lateral plate mesoderm
paraxial mesoderm
56
Eventually you will have a primitive streak and will regress as your __________ elongates to the posterior side
animal
57
Primitive streak will be removed eventually and your blastopore that will become primitive groove will become part of the ______
anus
58
FORMATION OF NOTOCHORD AND MESODERMAL SOMITES:
● Cells undergo ____________________ transformation and basal lamina breaks down
● Streak elongates towards the future head region (___________ extension)
epithelial-mesenchymal
convergent
59
Coming from the signals of the original primitive streak are moving towards the side, and you have your kidney, lateral plate mesoderm, and extra-embryonic membrane
○ They are moving _________
○ Involuting
■ Some of them are not only involute to its side but involute towards the __________ side
internally
anterior
60
- As the neural plate is forming, you already have your ____________ fold
- ____________, an area devoid of mesoderm because the most anterior mesoderm is the notochord
ectoderm
Proamnion
61
- Notochord will not reach the tip of your
ectoderm, just below the ectoderm is the hypoblast which will become __________
- Proamnion is an area where it will only have __________ and ___________
endoderm
ectoderm and endoderm
62
Eventually, you would have mesoderm, you have your notochord and other mesodermal tissues such as somites, which will be coming from the _______________
paraxial mesoderm
63
Difference here is that the segmental plate is not yet _____________ and the somites are coming from there and they have effectively separated, and if these are four somites, these would be considered 24 hours of development
segmented
64
- ______________ mesoderm will be the first one to form, and then eventually, you will have the intermediate developing in the middle of the paraxial lateral plate
- Lateral plate mesoderm will be separated into two: _________ mesoderm and ____________ mesoderm that would be going to extraembryonic membranes
Lateral plate
somatic and splanchnic
65
1. Becomes the ____________ endoderm of the foregut that migrates anteriorly and displaces the hypoblast in the germinal crescent
pharyngeal
66
2. Becomes the _______________ mesoderm
prechordal plate
67
3. Becomes the ________________ head process (forebrain and midbrain) and the notochord
chordamesoderm
68
5. Becomes the ________________ mesoderm
It will be partly for somatopleure or splanchnopleure
extraembryonic
69
- Primitive streak would __________ going to the prechordal plate, somites, more posterior somites, intermediate and lateral mesoderm
- You would have your bottle cells similar to the bottle cells of dorsal _____________ of the frog
involute
blastopore
70
- ____________ also migrates downward, forming the endoderm
- ____________ moves sideways
- ____________ is migrating in the middle, forming the three germ layers: ectoderm, mesoderm, and endoderm
Epiblast
Hypoblast
Mesoderm
71
REGRESSION OF THE PRIMITIVE STREAK:
Dorsal axis of the embryo is laid down
○ __________ and ________________ become established
○ __________ ectoderm begins to develop
notochord
neural precursors
head
72
______________ regresses to the posterior end to become the anus
○ Result is a flat embryo with 3 germ layers rather than a spherical embryo
Hensen's node
73
The avian body is separated from the yolk via the _____________
endoderm
74
- Eventually, your primitive streak would reach its maximum length, and it would regress
- ______________ occurs once your notochord has formed and your notochord is now elongated, making your primitive streak regress to the ________________ or going to the caudal end
regression
area pellucida
75
- In here, you would have a flat embryo, and it will develop at 48 hours of development; the embryo would move to the left, and it would now have its ____________
- You will be separating the yolk via endoderm
torsion
76
Three germ layers are:
○ Ectoderm
○ Mesoderm
○ Endoderm
77
Main difference between primitive streak and neural plate is the presence of ____________
notochord
78
- If notochord is present = ____________ area
- If notochord is absent = _____________ area
neural
primitive streak
79
Lateral plate mesoderm is divided into:
somatic and splanchnic mesoderm
80
Dorsal somatic mesoderm fuses with ectoderm
Somatopleure
81
Splanchnic mesoderm fuses with endoderm
Splanchnopleure
82
______________ mesoderm will be the precursor to the urinary and genital system
Intermediate
83
EPIBOLY OF THE ECTODERM:
● You have your ____________ cleavage, then posterior marginal zone forming hensen's node
● As Hensen's node moves forward, you will have a primitive streak in the ________
● Eventually, your primitive streak would narrow and would have ____________ and again forming three germ layers
● __________ will be displaced to the side as your endoderm is forming
● Eventually, epiblast will just be renamed as ______________
Meroblastic
midline
involution
hypoblast
ectoderm
84
Creation of the primitive streak establishes the _____________________ of the embryo
Begin at the tail end and move toward the head end
anterior-posterior axis
85
- Cells continue to _________ through the primitive streak, laying down the mesoderm layer
- At this point, the primitive regresses
ingress
86
- _____ and ______________ are present
- ________________ will be forming the notochord and will dorsalize the ectoderm
Fgf8 and Reitnoic Acid (Ra)
Sonic Hedgehog (Shh)
87
- __________ inhibits Wnt8 and also fgf8
- __________ would allow wnt8 to have your retinoic acids
Retinoic Acid
Fgf8
88
They are actually having a ________________ feedback. Once it reaches a certain area, it will no longer be available
cross negative
89
Fgf8 is only in the ___________
Shh is only in the ____________
Ra is only in the _____________ of
midline
posterior
anterior
lateral side
90
The _______ is more advanced because it is the first organ that forms and would be on the dorsal side
head
91
_____ gene activation begins when the mesodermal precursor cells are still in the epiblast
Hox
92
Hox genes are genes that are derived from _____________
drosophila
93
In drosophila, we only have Hox, however in _________ and ___________, we have Hox A, B, C, and D, and it would be considered added with a number
avians and mammals
94
Those with a number would be more anterior the lower the number - more _________ higher the number - more __________
anterior
posterior
95
● Hoxb4 - in ______ side
● Hoxb9 - in the ____ side
anterior
anterior
96
Hox genes are for the segmentation of animals; though we are not externally segmented, internally, we are segmented, and the most easily segmented embryonic structure that we have is the ________
○ __________ is segmented and eventually becomes a form of vertebra
somites
97
Gravitational determines the embryo axis, which would be anterior and posterior. As the egg rotates, you will be having your ________
chalaza
98
Ensures the anterior dorsal area/animal is always on top
Chalaza
99
Wnt8C and Vg1 (produced by PMZ) act together to induce expression of ________ (another secreted TGF-B protein) in the future embryonic epiblast next to Koller's sickle and the PMZ (dorsal side of the embryo)
Nodal
100
________- capable of inducing the accumulation of B-catenin
Wnt8c
101
Secretion of ___________ (antagonist of Nodal) by the primary hypoblast cells prevents primitive streak formation
○ That's why hypoblast are just more anterior
Cerberus
102
Streak secretes its own Nodal antagonist (lefty protein), thereby preventing any further ________________- from forming coming from the posterior marginal zone
primitive streaks
103
DORSOVENTRAL AXIS FORMATION:
● Subgerminal cavity has a ph of 6.5 (________)
● Albumin would have a ph of 9.5 (_______)
● Further, there is a membrane potential difference because water and sodium go from __________ toward your cells
● As such, you will have cells that are negative and cells that are more positive because having the potential difference of ________
acidic
basic
albumin
25mv
104
● Those that face the basic side will be the ________ side of the animal
● Those that face the acidic side will be the ________ side of the animal
● Dorsoventral axis is determined by the ___
dorsal
ventral
pH
105
The right side is where you have _________ and _________ that would inhibit the Sonic Hedgehog (Shh) and Cerberus
activin and BMP4
106
On the left side, you have Hensen's node forming _____________________ that allows Cerberus to form and will inhibit BMP4
Sonic Hedgehog (Shh)
107
○ Cerberus is only formed by _____
○ Cerberus allows BMP to form ____
Shh
nodal
108
____ is the protein or gene that needs to be transcribed in the left side
Pitx2
109
Cerberus, nodal, and pitx2 are all expressed on the _____ side of the animal
left
110
Avian is similar to fish with ______________ cleavage
discoidal meroblastic
111
The ________________ of your avian will be the posterior marginal zone
Nieuwkoop center
112
The early gastrula will be ____________
Hensen''s node
113
Late gastrula will ensure the correct arrangement of _______________
3 germ layers
114
As mesoderm and endoderm would
involute and migrate; Endoderm displaces the ___________
Once these 2 are formed, epiblast is
renamed as ectoderm
hypoblast
115
Characteristic vertebrae of _____________, which will have the tail, heart, wing bud, and limb buds
pharyngula
