4.2. Animal Development Flashcards
describes the changes in an organism from
its earliest beginnings through
maturity.
Development
______is
the initial event in development in sexual reproduction.
Union of male and female gametes.
Recombination of paternal and maternal genes.
Restoration of the diploid number (two sets of chromosomes).
Fertilization
The diploid cell resulting from
fertilization is now
called a___.
zygote
\_\_\_\_ rapid cell divisions following fertilization. Very little growth occurs while the cells are dividing. Each cell called a \_\_\_\_
Cleavage; blastomere
– the name given to the solid
ball of cells that results from
cleavage.
First __ divisions.
Morula ;5-7
As divisions continue, a fluid filled
cavity called ____ , forms within the
embryo.
The resulting hollow ball of cells is now called a ____
blastocoel; blastula
The morphogenetic process called ___ rearranges the cells of a
blastula into a three-layered (triploblastic) embryo, called a ____, that has a primitive gut (____).
gastrulation; gastrula ;archenteron
The ____ is the first opening in
the embryo – the point of invagination
during gastrulation.
This will eventually become either the mouth or the anus.
One end of the gut-tube or the other.
The space that forms during this time is the primitive gut, the _____
blastopore; archenteron.
The three tissue layers produced by
gastrulation are called _____.
embryonic germ layers
The _____ forms the outer layer of
the gastrula.
Outer surfaces, neural tissue
ectoderm
The ____ lines the embryonic
digestive tract
endoderm
The ____ partly fills the space
between the endoderm and ectoderm.
Muscles, reproductive system
mesoderm
Gastrulation in a ____ produces an
embryo with a primitive gut (archenteron) and three germ layers.
sea urchin
Result is again an embryo with gut & 3 germ layers.
Gastrulation in ___ is more complicated due to the moderate amount of yolk present in the egg.
Blastula wall more than one cell thick.
the frog;
Gastrulation in ___ is affected by the large amounts of yolk in the egg.
Embryo essentially sits on top of large mass of yolk.
the chick
– a groove on the surface along the
future anterior-posterior axis.
Functionally equivalent to blastopore lip in frog.
Primitive streak
In mammals the blastula is called a ___.
____ will become the embryo
while ___ becomes part of the
placenta.
blastocyst; Inner cell mass; trophoblast
Gastrulation in ___ involves the
inner cell mass and is similar to that of
the chick due to the fact that
mammalian ancestors and early
mammals laid eggs.
The large mass of yolk may be gone, but
the developmental pattern remains.
mammals
Shortly after fertilization, the zygote undergoes a series of rapid cell divisions. This is called ___
cleavage
During cleavage, each cell in the embryo is called a
blastomere
The solid ball of cells that results from
cleavage is called
Morula
A fluid filled space called the
blastocoel forms inside the
embryo - at this point it is a
blastula
The stage that results in three
germ layers and a primitive gut is
the
gastrula
The difference in gastrulation
found in different types of animals
is due primarily to:
a. The amount of yolk present
b. The size of the blastomeres
c. Development in different
species is completely
unrelated
a.The amount of yolk present
