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Invertebrate Zoology > Eggs and Embryos > Flashcards

Eggs and Embryos Flashcards

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1
Q

what is en egg/ ovum?

A

single cell capable of developing into a new individual

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2
Q

How is an egg shaped (3)?

A

polarized along an animal-vegetal axis

vegetal pole- formation of nutritive organs (digestive system)

animal pole (top)- all other regions of the embryo

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3
Q

What is a yolk?

A

genetic information necessary to direct development and nutrient material in fertilized ovum

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4
Q

How are ovums categorized?

A

amount and location of yolk

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5
Q

What are isolecithal eggs?

A

relatively small amount of yolk that is more or less evenly distributed throughout the cell

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6
Q

What are telolecithal eggs?

A

yolk is concentrated toward the vegetal end

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7
Q

What are controlecithal eggs?

A

yolk is concentrated in the center

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8
Q

What is vitellogenesis?

A

yolk production

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9
Q

What is the longest phase of egg production?

A

vitellogenesis

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10
Q

How do r-selected and k-selected species differ in vitellogenesis?

A

r-selected species use rapid conversion of food into egg production, while k-selected utilizes slower pathways

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11
Q

What is a zygote?

A

fertilized egg

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12
Q

What is a cleavage and what does it result in?

A

initial cell divisions of a zygote

results in cells called blastomeres

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13
Q

What is holoblastic cleavage, and what kind of eggs are they seen in?

A

cleave pass completely through the cell, producing separated blastomere (isolecithal and weaklly telolecithal)

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14
Q

What is meroblastic cleavage, and what kind of eggs are they seen in?

A

cleavage does not pass through the yolk, and is not fully separated (strongly telocithal)

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15
Q

What do centrolecithal egg cleavage depend on?

A

yolk amount`

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16
Q

What is subequal cleavage?

A

when blastomeres are only slightly different in size

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17
Q

Macromeres vs micromeres

A

macromeres- larger cells in the vegetal pole due to unequal cleavage

micromeres- smaller cells in the animal pole

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18
Q

What is longitudinal division?

A

cleavage planes that pass through/ parallel to the animal vegetal axis

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19
Q

What is transverse division?

A

cleavage planes pass at a right angle to the axis

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20
Q

What is radial cleavage?

A

strictly longitudinal and transverse division

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21
Q

How are blastomeres aranged in radial cleavage?

A

blastomeres arranged in rows parallel/ perpendicular to the animal-vegetal axis

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22
Q

What is spiral cleavage?

A

first two divisions are equal/ subequal longitudinal division

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23
Q

What is dextropic division?

A

displacement of cells near animal pole in a clockwise direction (division from 4-8 cells)

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24
Q

What is levotropic division?

A

displacement in a counterclockwise, from 8-16 cells

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25
What is a rosette?
topmost cells at the embryo’s apex
26
annelid vs molluscan cross
annelid cross- micromeres producing right angles to the rosette molluscan cross- an additional annelid cross
27
What does the first three quartet of micromeres give rise to?
ectoderm
28
How are cells numbered (4)?
ABCD- division of the original cell 1234- generation of micromere abcd- numbering of micromeres q- collective micromeres of a generation (1q refers to all the micromeres of the first generation)
29
What is determinate cleavage?
spiral cleavage where if one blastomere is removed, embryo may fail to develop and cannot be displaced
30
What is a mosaic ova?
fates of regions of undivided cells can be mapped
31
What is indeterminate cleavage?
blastomere can be separated and will develop normally ; usually radial
32
What is regulative ova?
ova that can regulate to accommodate lost blastomeres and cannot be mapped prior to division
33
How many cells is basic body plan determined?
104 cells
34
What is fate maps?
- embryonic material apportioned into specific cell groups (founder regions) that forms a territory within where structures develop
35
What is a blastula?
embryonic stage preceding the formation of embryonic germ layers
36
What is a holoblastic blastula?
hallow or solid ball of cells
37
What is a coeloblastula?
hollow ball of cells with a one cell layer thick wall
38
What is a blastocoel?
primary body cavity
39
What is a stereoblastula?
solid ball of blastomeres
40
What is a discoblastula?
meroblastic cleavage resulting in a cap of cells in the animal pole
41
What is a periblastula, and what is it similar to?
centrolecithal ova undergoing odd cleavage pattern- similar to a coeloblastula filled with no cellular yolk
42
What is gastrulation?
multilayer formation fo the blastula
43
What is a gastrula?
resulting embryo after gastrulation
44
What do the ectoderm, endoderm, and mesoderm form?
ectoderm- forms nervous system and the outer skin endoderm- forms main portion of the gut mesoderm- forms coelomic lining, circulatory system, internal support structures, and the musculature
45
What is invagination, and what does it form?
gastrulation method in coeloblastulae, where one region puches inward as a sac within the blastocoel- forms the endoderm
46
What is an archenteron?
sac formed by invagination; embryonic gut
47
What is a blastopore?
opening in the archenteron
48
What is a stomodeal?
ectoderm lining the interior of the blastopore if it becomes the mouth
49
What is proctodeal?
stomodeal version if anal blastopore
50
What is coelogastrula?
coeloblastula invaginated
51
What is a stereogastrula?
solid gastrula of cnidarian coeloblastulae
52
What is ingression?
cells detaching from the stereogastrula wall and migrating into the blastocoel
53
Unipolar vs multiplolar ingression
unipolar if occurs in the vegetal pole multipolar if occurs in the whole blastula
54
What is delamination, and what does it produce?
cells of the blastula dividing with cleavage planes that are parallel to the surface produces a solid mass of endoderm surrounded by a layer of ectoderm
55
What is epiboly?
-gastrulation method in holoblastic stereoblastulae
56
Three steps in epiboly
gastrulation leads to rapid growth by a sheet of ectodermal cells around endoderm blastopore forms where the edges of sheet converges at the vegetal pore archenteron forms secondarily as a space within the developed endoderm
57
What is involution?
- gastrulation process that follows formation of discoblastula
58
What is ectomesoderm?
mesoderm deriving from the ectoderm
59
What is endomesoderm?
mesoderm deriving from the mesoderm
60
What is a mesoglea?
loosely organized mesenchyme consisting of a gel matrix containing cells and fibers
61
What is a mesentoblast?
4d micromere proliferates as mesoderm between archenteron and body wall
62
What is schizocoely?
body cavity arising from solid masses derived from a mesentoblast, where the mesoderm enlarges and splits
63
what is enterocoely?
mesoderm formation from the archenteron
64
What is archenteric pouching?
pouch forms from gut wall and pinches off as a coelomic compartment
65
What does archenteric pouching result in?
protocoel mesocoel metacoel
66
What is morphogenesis?
cell specialize and sport themselves to form organs and tissues
67
What is induction?
communication between cells during morphogenesis
68
Three examples of induction
signaling molecules like hormones, growth factors, and morphogens actual contact between cell surfaces gap junctions

Invertebrate Zoology (18 decks)

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