Chapter 44: Animal Development Flashcards
1
Q
Animal development
A
transformation from a single egg, zygote (diploid [2n] fertilized egg) via cell division, cell movement, cell specialization, pattern formation and apoptosis
2
Q
What are the stages of development?
A
cell division–>cell expansion–>growth–>cell differentiation–>creation of tissue–>creation of organs
3
Q
What are the 4 processes of development?
A
- determination
- Differentiation
- Morphogenesis
- Growth
4
Q
Differentiation
A
the process by which different types of cells arise
5
Q
Morphogenesis
A
organization and spatial distribution of differentiated cells
6
Q
Growth
A
increase in body size by cell division and expansion
7
Q
What are the ways in which morphogenesis occurs?
A
cell division, cell expansion, cell movements, apoptosis
8
Q
Cell fate
A
which type of tissue the cell will ultimately become. cell fate is usually determined quite early
9
Q
Fertilization
A
gametes, sex cells
10
Q
Haploid
A
one set of chromosomes
11
Q
Diploid
A
two sets of chromosomes
12
Q
Gametes are produced when?
A
meiosis
13
Q
how do the gametes get their chromosomes?
A
each parent contributes a set
14
Q
How is zygote produced?
A
fusion of gametes
15
Q
What is the human egg protected by?
A
cumulus and zona pellucida
16
Q
what does fertilization do?
A
- blocks entry of additional sperm
- stimulates ion fluxes across membranes
- changes pH of the egg
- increases egg metabolism and protein synthesis
- initiates cell division
17
Q
what is contained in eggs
A
large, well stocked with organelles, nutrients, transcription factors, and mRNA
18
Q
Cumulus
A
keeps out unhealthy sperm
19
Q
What happens during fusion?
A
2 pronuclei lose their nuclear membranes and fuse together to form diploid zygote
20
Q
Vegetal hemisphere
A
lower half of egg, where nutrients are concentrated
21
Q
Animal hemisphere
A
opposite end of the egg, has pigments and contains nucleus
22
Q
Cleavage
A
blastula formation, cleavage in mammals is unique, specific blasters generate specific tissues and organs
23
Q
Gastrulation
A
three germ layer formation
24
Q
Organogenesis
A
formation of an organ system
25
Neurulation
formation of a nervous system
26
Mosaic development is
determinate
27
Regulated development is
indeterminate
28
Cleavage
early cell divisions with no cell growth. embryo becomes a solid ball of small cells.
29
Blastocoel
a central fluid-filled cavity that forms in the ball
30
Blastula
developed embryo
31
Blastomeres
the cells of the blastula
32
complete cleavage
eggs with little yolk
33
incomplete cleavage
occurs in eggs with a lot of yolk when cleavage furrows don't penetrate
34
Discoidal cleavage
embryo forms as a blastodisc that sits on top of the yolk
35
Superficial cleavage
variation of incomplete cleavage in insects
36
Syncytium
cell with many nuclei
37
Why is there little increase in overall volume during cleavage?
because the blastomeres become progressively smaller
38
What influences cleavage?
amount of yolk, orientation of mitotic spindle,
39
Blastocyst
a dense inner cell mass on top of a hollow blastocoel, surrounded by a trophoblast
40
Mammalian cleavage is slow or fast?
slow and asynchronous
41
what happens when the zygote reaches the 8 cell stage?
blastomeres change shape and maximize contact with one another to form a tight ball
42
What happens at the 32 cell stage?
Inner cell mass- becomes the embryo OR trophoblast forms from outer cells
43
Trophoblast
sac that forms from the outer cells. its cells secrete fluid to create the blastocoel cavity, with the inner cell mass at one end.
44
Mosaic development
loss of blastomeres results in loss of later structures
45
Regulated development
loss of blastomeres does not deleteriously affect development because the remaining cells compensate for the loss (ex: in human blasters but not inner cell mass)
46
Mosaic development
each blastomere contributes certain aspects to the adult animal (roundworms) removing one blastomere will harm the embryo
47
Regulative development
other cells compensate for any lost cells (many vertebrates) one blastomere removed won't harm embryo
48
Blastomeres
separate into two groups, each can become an embryo
49
Monozygotic twins
come from same zygote and are identical
50
Nonidentical twins
from two eggs fertilized by two sperm
51
Gastrulation
three germ layer formation - from hollow ball to tube within a tube
52
Gastrulation
formation of a gastrula
53
Gastrula
embryo with gut connected to outside by mouth or anus "opening"; a blastopore
54
Cells of blastula reorganize into how many layers?
three germ layers.
55
What are the three germ layers?
1. Ectoderm
2. Endoderm
3. Mesoderm
56
Germ layers are fated to develop into specific adult tissues
"determined" to develop this way … later develop into specific tissues through differentiation
57
Ectoderm
fates include nervous system and epidermis of skin
58
Endoderm
fates include inner linings of gut and respiratory system, liver, pancreas, urinary bladder
59
Mesoderm
becomes the skeletal system, circulatory systems, kidneys, gonads, blood cells, muscles, dermis of skin
60
What does Gastrulation form
the gastrula: an embryo with an internal cavity "primitive intestine"
61
Invagination
creates a primitive intestinal cavity (archenteron) exposed to the outside through the blastopore that later forms either an anus or mouth depending on organism
62
Deuterosomes
blastopore forms anus, mouth later forms from second opening
63
Protosomes
blastopore forms mouth, anus later forms from second opening
64
Gastrulation in the Bird: what happens to blastoderm cells?
they migrate to the primitive streak, move through it into the blastocoel to form the endoderm and the mesoderm
65
Blastula in the birds
flat disk of cells on top of the yolk
66
Hypoblast
a continuous layer that will contribute to extra embryonic membranes, formed from cells that enter the fluid space between blastodisc and yolk
67
Epiblast
overlying cells that will become the embryo, move toward the midline and form a ridge called the primitive streak
68
Hensen's node
equivalent of the amphibian dorsal lip and contains many signaling molecules.
69
Trophoblast:
that layer surrounding the blastocoel
70
Where does fertilization occur in mammals?
oviduct; cleavage occurs as the zygote travels down oviduct to uterus
71
Implantation: when does it occur?
when the trophoblast adheres to the endometrium (uterine lining)
72
Ectopic (tubal) pregnancy
implantation occurs in the oviduct: zona pellucida usually prevents this
73
blastocyst
the cell mass that is implanted in the maternal uterus
74
Trophoblast
outer layer of the blastocyst that becomes the placenta
75
Determination
influenced by gene expression and the extracellular environment. it's a commitment.
76
Differentiation
changes in biochemistry, structure, and function that result in different cell types
77
Cell potency
potential to differentiate into other cell types
78
Totipotent
can differentiate into any cell type (early embryo)
79
Pluripotent
can develop into most cell types, but cannot form new embryos
80
Multipotent
can differentiate into several related cell types
81
Unipotent
can produce only one cell type: their own (mature organism)
82
Organogenesis
the making of organs
83
Chordamesoderm
the mesoderm closest to the midline
84
Notochord
provides support for the embryo
85
What does the chordamesoderm do?
has organizer functions and induces the ectoderm to form the nervous system
86
Neurulation slide 54 & 56
forming of nervous system; process by which external sheet of cells (neural plate) develops into an internal tube (neural tube) that later develops into brain and spinal chord
87
Chordates
1. Invertebrates
| 2. Vertebrates
88
What are some examples of invertebrates?
tunicates and branchiostoma
89
What are some examples of vertebrates?
fishes, reptiles, mammals, amphibians, birds, humans
90
somites
blocks of mesodermal cells that produce cells that become the vertebrae, ribs, muscles, and lower skin layer. ; guide peripheral nerve development
91
Determination
germ layers are fated to develop into specific tissues through differentiation
1. cytoplasmic segregation
2. embryonic induction
92
Determination by cytoplasmic segregation
cytoplasmic components of eggs are unevenly distributed into separate cells or parts of cells to cause cell determination
93
Determination by embryonic induction
interactions with other cells/tissues causes determination. the inducer is the specific chemical signal
94
Is the fate of a cell in the early embryo already determined?
Cell fates in the early embryo are not determined, but can change depending on the environment
95
Do different regions in the fertilized egg and the embryo have different developmental potential?
the animal and vegetal pole halves differ in their developmental potential
96
Cytoplasmic segregation, aka
unequal cytokinesis
97
Induction
cell-to-cell communication
98
cytoplasmic segregation
factors within a zygote or egg are not distributed evenly and end up in different daughter cells after division; polarity with a top and bottom
99
Animal development: which is top and which is bottom/
animal pole=top
| vegetal pole=bottom
100
What happens if a sea urchin an eight-cell embryo is cut vertically?
develops into 2 small larvae
101
What happens if a sea urchin eight-cell embryo is cut horizontally?
bottom develops into larva, top remains embryonic
102
Are cytoplasmic factors necessary for development localized in the fertilized egg?
cytoplasmic factors in the gray crescent are crucial for normal development
103
When is presumptive epidermis determined to follow a particular developmental path?
during gastrulation, presumptive neural ectoderm becomes determined to develop into nervous system
104
Can some cells induce other cells to follow a particular developmental path?
the dorsal lip can induce other cells to participate in embryogenesis
