Reproduction and development Part 6 Flashcards
What are the embryonic development stages
- Fertilization, which forms a zygote.
- Cleavage stage- a series of mitoses divide the zygote into a many-celled embryo
- Embryo is transformed into a hollow ball of cells called a blastula
- The blastula then undergoes rearrangements into a three-layer embryo called the gastrula
Cleavage stage
a series of mitoses divide the zygote into a many-celled embryo
blastula
hollow ball of cells
produced after 5 - 7 cell divisions
gastrula
three-layer embryo
During organogenesis, local changes in cell shape and large-scale changes in
cell location generates the rudimentary organs
In fertilization
-sperm penetrates the protective layer around the egg. – -Molecules on the egg and sperm surface bind to one another
- Fertilization initiates metabolic reactions that trigger the onset of embryonic development, activating the egg
changes at the egg surface prevent polyspermy
the entry of multiple sperm nuclei into the egg
Sperm entry triggers a release of Ca2+ activating the egg and triggering the
cortical reaction
cortical reaction
The slow block of polyspermy
activation leads to events such as
protein synthesis, that precede the formation of a diploid nucleus
Fertilization is followed by
cleavage
cleavage
a period of rapid cell division without growth.
Cleavage partitions in the cytoplasm of one large cell into smaller many cells
blastocoel
fluid-filled cavity
conception
fertilization of an egg by a sperm occurs in the oviduct
What happens in sperm binding
a cortical reaction is triggered which results in a slow block to polyspermy
