Early Craniate Morphogenesis Flashcards
(81 cards)
1
Q
Egg types according amount of yolk
A
a. microlecithal
b. mesolecithal
c. macrolecithal
2
Q
-very little yolk
- amphioxus, therian mammals
A
microlecithal
3
Q
- moderate amount of yolk
- amphibians
A
mesolecithal
4
Q
- large amount of yolk
- reptiles, monotremes
A
macrolecithal
5
Q
Egg types according to yolk distribution
A
a. isolecithal
b. telolecithal
6
Q
- yolk is evenly distributed in the cytoplasm
- seen in microlecithal egg
A
isolecithal
7
Q
- yolk is concentrated in one pole (vegetal pole_
- seen in mesolecithal ang macrolecithal eggs
A
telolecithal
8
Q
opposite pole containing the nucleus and yolk free cytoplasm
A
animal pole
9
Q
- animals that lay eggs (spawn)
- eggs contain sufficient amount of yolk and albumen
A
Oviparous
10
Q
Oviparous
- eggs contain sufficient amount of yolk and albumen
to ___ the ___ into a free living
organisms that is able to take food orally
A
support, development
11
Q
Oviparous macrolecithal
A
fully formed when hatched (birds)
12
Q
Oviparous mesolecithal
A
young hatch in a larval stage (frog)
13
Q
Oviparous microlecithal
A
young hatch in a free-living and self-nourishing stage (amphioxus)
14
Q
animals that give birth to offspring
A
viviparous
15
Q
type of viviparity
- mother only provides protection and oxygen, while nourishment stored in the egg (viviparous shark)
A
ovoviviparity
16
Q
Type of viviparity where embryos are dependent on maternal tissues for nourishment, oxygen, secretion (placentals)
A
euviviparity
17
Q
Trophotaeniae (trophe= ___, taenia= ___)
A
nutrition, band
18
Q
- fertilization takes place within the body of the female
(viviparous craniates) - Eggs are covered by impenetrable shell before being
extruded (reptiles)
A
internal fertilization
19
Q
___ ___ is needed to introduce sperm into the
female reproductive tract.
A
intromittent organ
20
Q
- millions of sperm cells are shed over the eggs as the eggs
are being extruded - Oviparous fishes, frogs and toads
A
external fertilization
21
Q
Process of Life
A
Gamete formation > Fertilization > Cleavage > Gastrulation > Organ formation > Growth, Tissue Specialization
22
Q
Repeated mitotic cell division of the zygote
A
Cleavage or segmentation
23
Q
Cleavage and blastula
* embryo experience little or no
___ in size
* multicelled
and hollow sphere
or ___ is formed
A
growth, blastula
24
Q
cells resulting from the early cleavage division of the ovum
A
blastomeres
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cavity of blastula
blastocoele
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Types of Cleavage
1. Holoblastic cleavage
2. Meroblastic cleavage
3. Discoidal cleavage
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cleavage where yolk is sparse (microlecithal)
Holoblastic cleavage
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Holoblastic cleavage
*mitotic furrow ____ from animal to
vegetal pole
* microlecithal
* mesolecithal
- pass through the entire zygote
- blastomere are equal size
- yolk-laden cells in vegetal pole divide slower and larger
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cleavage where yolk is plentiful (macrolecithal) cell division is impeded by the presence of yolk
Meroblastic
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extensive yolk material at vegetal pole remains undivided by mitotic furrows
discoidal cleavage
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Mechanism of cleavage (LIICF)
- localize expansion of cortex
- increased stiffness of cortical cytoplasm
- increased tangential force
- contractile nature of region near cortex
- formation of new cell membrane
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____ follows fertilization
cleavage
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zygote is partitioned into ___
blastomeres
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After the cleavage has produces over 100 blastomeres, the embryo is called a ___
blastula
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Continued cleavage produces __
morula
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The blastoderm surrounds a fluid filled or yolk filled cavity called
blastocoel
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Blastulation
- Pre embryonic cleavages make use of the abundant ___ of the fertilized egg as the cells rapidly divide without changing the ___ ___.
cytoplasm, total volume
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Blastulation
- The rearrangement of the cells in the mammalian blastula to two layers, the ____and the ____, results in the formation of the blastocyst
inner cell mass and trophoblast
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The formation of gut, but in a broader sense
gastrulation
40
Gastrula = ___
belly
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gastrulation leads to formation of
trilaminarembryo
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Gastrulation
- the ____ ____ is the visible feature which represents site of cell migration to form more layers
primitive streak
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formation of neural tube from the ectoderm of the embryo
neurulation
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Organogenesis
- Alongside the neural tube, the mesoderm develops distinct paired
structures called ___ that develop into dermis, skeletal muscle, and
vertebrae.
somites
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Four compartments of somites
sclerotome, myotome, dermatome, and syndetome
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Derivative of ectoderm
- epidermis of skin
- epithelial lining of mouth and rectum
- cornea and lens of the eyes
- nervous system
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Derivative of endoderm
- epithelial lining of digestive tract
- epithelial lining of respiratory system
- pancreas, thyroid and parathyroid, thymus, urogenital
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derivatives of mesoderm
- notochord
- skeletal and muscular system
- circulatory and lymphatic
- excretory system
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Solution to reproduction in a dry environment
amniote embryo
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develop in a fluid-filled sac within shell or uterus
amniote embryo
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avian version of blastula
blastodisc
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blastodisc, when becomes arranges into
epiblast and hypoblast
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during gastrulation some cells of the epiblast migrate towards the ___ of the embryo through the primitive streak
towards
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In early organogenesis the ___ is formed as lateral folds pinch the embryo away from the yolk.
archenteron
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The ___ (formed mostly by hypoblast cells) will keep
the embryo attached to the yolk.
yolk stalk
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Mammalian development
1. Blastocyst reaches uterus
2. Blastocyst implants
3. Extraembryonic membranes starts to form
4. Gastrulation produces three-layered embryo
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Begins with formation of the neural tube, notochord, and somite
organogenesis
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Masses of mesoderm that can be found distributed among the two sides of the neural tube
Somites
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Vertebrates whose vertebrates possess extraembryonic membrane
Amniotes (reptiles, birds, mammals)
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Embryos without extraembryonic membrane
Anamniotes (fishes, aphibians)
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Four extraembryonic membranes
- yolk sac
- amnion
- chorion
- allantois
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Most primitive membrane that surrounds the yolk, empties into the midgut
yolk sac
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Yolk sac
- highly vascular, ___ arteries and veins are continuous with the
circulatory channel within the embryo
vitelline
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Innermost layer that make up the amniotic sac
Amnion
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Surrounds the embryo within the amniotic sac
Amniotic fluid
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Amniotic fluid
- Metabolic water from ____
- buffers the fetus against ____
- help prevent ___ in embryos (oviparous)
embryonic tissues, mechanical injury, dessication
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Lies in intimate relationship with eggshell or lining of mother's uterus
Chorion
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Extension of the hindgut of amniote embryos
Allantois
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When allantois comes in contact with inner surface of the chorion
chorioallantoic membrane
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When the allantois comes in direct contact with the lining of the maternal uterus
Chorioallantoic placenta
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Composite organ formed of maternal and fetal tissues serves as site for exchange between parent and embryo
placenta
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Placenta based on composition
1. yolk sac placenta
2. choriovitelline placenta
3. chorioallantoic placenta
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yolk sac serves as part of a placenta, due to absence of amnion, chorion or allantois
yolk sac placenta
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yolk sac and chorion in direct contact with maternal uterus
choriovitelline placenta
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chorion and allantois in direct contact with maternal uterus
chorioallantoic placenta
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Placenta based on intimacy
1. Contact or nondeciduous placenta
2. deciduous placenta
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In simple contact with the uterine lining (endometrium), no shedding of lining at birth
contact placenta
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chorionic villi becomes rooted to endometrium, fetal part of placenta disengages (shed)
deciduous placents
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Placenta based on chorionic villi
1. Cotyledonary placenta
2. Zonary placenta
80
In isolated patches, commonly found in sheep and cows
cotyledonary placenta
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In a band encircling the sac. Commonly found in cat, dog, or seal
zonary placenta
