Animal Development Flashcards
1
Q
a series of mitotic divisions and cell migrations that transform the zygote into a blastula
A
cleavage
2
Q
blastula
A
“hollow ball” of cells
3
Q
hallow center of blastula
A
blastocoel
4
Q
there is little increase in the overall volume during cleavage because the – become progressively smaller
A
blastomeres
5
Q
the cells of a blastula
A
blastomeres
6
Q
the amount of – influences cleavage
A
yolk
7
Q
fertilization stimulates – across the egg membrane
A
ion fluxes
8
Q
fertilization sets up blocks to the entry of – into the egg
A
additional sperm
9
Q
fertilization changes the –of egg cytoplasm
A
pH
10
Q
fertilization increases egg – and stimulate protein synthesis
A
metabolism
11
Q
fertilization initiates the rapid series of – that produce a multicellular embryo
A
cell divisions
12
Q
– is well stocked with organelles, nutrients, transcription factors, and mRNA
A
egg cytoplasm
13
Q
sperm contributes –
A
DNA (haploid nucleus) and centriole (origin of primary cilia)
14
Q
centriole becomes the zygote’s –
A
centrosome which organizes the mitotic spindles for subsequent cell divisions
15
Q
molecules in the cytoplasm of amphibian egg are – distributed
A
not homogenously
16
Q
sperm entry establishes – of the zygote
A
polarity
17
Q
the nutrients in an unfertilized frog egg are dense yolk granules that are concentrated by gravity in the lower half of the egg called
A
vegetal pole
18
Q
the haploid nucleus of egg is located at
A
animal pole
19
Q
the animal cortical cytoplasm is
A
pigmented
20
Q
frog egg is – symmetrical
A
radially
21
Q
when a sperm binds to and enters a frog’s egg the radial symmetry turns into a – symmetry
A
bilateral
22
Q
cortical cytoplasm rotates toward
A
the site of sperm entry
23
Q
in amphibian eggs, cortical rotation and rearrangement of the cytoplasm after fertilization create the – opposite the point of sperm entry
A
gray crescent
24
Q
gray crescent marks the location of
A
important developmental events
25
the centriole from sperm initiates
cytoplasmic reorganization (causes microtubules in vegetal pole to form a parallel array that guides movement of the cortical cytoplasm)
26
sequence of early cell divisions that transform the diploid zygote into a mass of undifferentiated cells that will develop as the embryo
cleavage
27
occurs in most eggs that have little yolk
complete cleavage
28
frogs undergo -- complete cleavage
unequal
29
occurs in species in which the egg contains a lot of yolk and the cleavage furrows do not penetrate it all
incomplete cleavage
30
is a type of incomplete cleavage common in fishes and birds in which the embryo forms a disc of cells (blastodisc) that sits on top of the dense yolk mass
discoidal cleavage
31
variation of incomplete cleavage that occurs in fruit flies
superficial cleavage
32
a single cell with many nuclei
syncytium
33
the nuclei eventually migrate to the periphery of the egg, after which the plasma membrane grows inward, creating a -- by partitioning the nuclei into individual cells surrounding a core of yolk
blastoderm
34
what influences the pattern of cleavage
amount of yolk and orientation of mitotic spindle (determined by maternal genome)
35
-- cleavage occurs in mammals
rotational
36
mammalian cleavage is slow and asynchronous because
blastomeres do not undergo mitosis at the same time
37
when the zygote reaches the 8-cell stage, the blastomeres change shape to maximize their surface contact with each other forming -- and become a compact mass of cells
tight junctions
38
At the 32-cell stage, cells separate into two groups:
inner mass and trophoblast
39
will become embryo
inner mass
40
surrounding outer cells become an encompassing sac that secretes fluids to create the blastocoel cavity with the inner cell mass at one end
trophoblast
41
at the 32-cell stage the embryo is called a
blastocyst
42
specific blastomeres generate specific
tissues and organs
43
loss of blastomeres results in loss of later structures
mosaic (determinate) development
44
loss of blastomeres doesn't deleteriously affect the development because the remaining cells compensate for loss
regulated (undeterminate) development
45
cells move to new positions adn form the three germ layers from which differenitated tissues develop
gastrulation
46
inner most germ layer, digestive tract, respiratory tract, pancreas, thyroid, liver
endoderm
47
outer germ layer, nervous system and epidermis of skin
ectoderm
48
middle layer, skeletal muscle, circulatory system, kidneys, gonads, blood cells, dermis of skin
mesoderm
49
embryonic or unspecialized cells that migrate to other tissue layers
mesenchyme cells
50
sea urchin gastrulation, some cells change shape and move inward to form the -- other cells break free becoming primary --
archenteron, mesenchyme
51
opening created by the invagination of the vegetal pole
blastopore
52
blastopore becomes anus
deuterostomes (sea urchins and vertebrates)
53
blastopore becomes mouth
protostomes (earthworm and insects)
54
the embryo develops only partially in the uterus then finishes outside in a pouch (marsupium)
non Eutherian mammals
55
nutrient and waste exchange in eutherian mammals occur via the
placenta
56
surround the vertebrate embryo
extraembryonic membranes
57
encloses yolk within egg
yolk sac
58
yolk is -- by cells of the yolk sac and the nutrients are transported to the embryo
digested
59
a sac for waste storage
allantois
60
surrounds the embryo, forming the fluid-filled amniotic cavity that protects the embryo
amnion
61
forms a continuous membrane just under the eggshell; reduces water loss and exchanges gases
chorion
62
the amniotic egg provides an -- environment for development of the embryo
aqueous
63
the yolk sac is the -- and -- layers that surround the yolk to absorb its nutrients
mesoderm and endoderm
64
the -- forms the umbilical cord in eutherian mammals
allantois
65
chorion layers
ectoderm and mesoderm
66
amnion layers
mesoderm and ectoderm
67
allantois layers
mesoderm and endoderm
68
in placental mammals, the first extraembryonic membrane to form is the --
trophoblast
69
the inner cell mass consists of -- and --
hypoblast and epiblast
70
trophoblast cells interact with the -- and adhesion molecules and adhesion molecules attach them to the --
endometrium, uterine wall
71
the trophoblast -- into the uterine wall and sends out -- to increase contact with maternal blood
burrows, villi
72
hypoblast cells form the
chorion
73
the placenta develops from the -- and -- tissues
chorion and uterine
74
the epiblast produces the --
amnion
75
rupturing of the amnion and chorion and loss of the -- = water break
amniotic fluid
76
the process of embryonic/fetal development from fertilization to birth (parturition)
gestation or pregnancy
77
first trimester =
"embryonic" development
78
in the first trimester the embryo becomes a --
fetus
79
heart begins to beat by week
four
80
limbs form by week
eight
81
first trimester is a time of -- cell division and tissue differentiation
rapid
82
second trimester
limbs elongate
fingers, toes, and facial features form
nervous system develops rapidly
first fetal movements are felt
83
third trimester
internal organs mature
brain goes through sleep-wake cycles
birth occurs when lungs are mature
84
increased ratio of -- to -- at the end of 3rd trimester
estrogen to progesterone
85
human chorionic gonadotropin is produced by the chorion during
first trimester
86
During the first trimester, hCG keeps the -- functional which keeps producing high E and P levels to prevent ovulation from occuring
corpus luteum
87
Due to its highly negative chard, hCG may repel the -- of the mother, protecting the fetus during the first trimester
immune cells
88
hormonal changes during the first trimester cause
"morning sickness"
89
rapid fetal development occurs during the -- trimester
second
90
during the second trimester, the placenta produces lots of E and P from -- (eg the steroid biosynthetic pathway) which continues to inhibit ovulation and menstruation
circulating androgens
91
during the third trimester the -- ratio increases
E/P
92
amniotic fluid is withdrawn
amniocentesis
93
amniocentesis - chromosomal abnormalities, sex determination, week --, risk 0.5% miscarriage
14-16
94
not as invasive as amniocentesis during week -- risk 0.5-1% miscarriage
chorionic villus sampling, 10-12
95
ultrasound early week 6-10 = / week 10-13 =
vaginal, belly
96
ultrasound measures
nuchal translucency
97
an accumulation of fluid at the base of the baby's neck that is expected to be seen in all pregnancies
nuchal translucency
98
a nuchal translucency measurement above -- is considered abnormal
3.0 - 3.5mm
99
an increased nuchal translucency is associated with a higher risk for --
chromosome abnormality or structural defect
100
absence of testosterone and MIH -->
mullerian duct system (fallopian tubes and uterus)
101
presence of testosterone and MIH -->
wolffian duct system (epididymis and vas deferens)
102
during the first trimester in humans, embryonic gonadal tissue (the mesoderm) develops into -- due to the expression of the gene on the Y chromosome
testes
103
5-alpha DHT promotes the development of -- into male genitalia
undifferentiated external genitalia
104
XY gonads produce androgen -->
male
105
XX no androgen -->
female
106
XY but androgen receptor defect -->
inside testes outside female
107
XY 5-alpha reductase deficient -->
internal male, external micropenis
108
XY no androgen -->
fertile female
109
XX androgen production
oversized clitoris and fused labia
110
XY androgen/no-androgen
fertile male, micropenis
111
Later in fetus XY no androgen
baby boy with micropenis
112
a general term used for a variety of conditions in which a person is born with a reproductive or sexual anatomy that doesn't seem to fit the typical definitions of female or male
intersex
113
consequences of normalizing procedures
loss of sensory tissue, memories of child sexual trauma, surgeries intensify the feeling of shame and alienation they are meant to eliminate
