CB36: Fertilisation to formation of blastocyst Flashcards
What are the 4 major events in mammalian vertebrate embryo development?
- Formation of blastula
- Gastrulation
- Neurulation
- Organogenesis
At what stage does the zygote start to lose totipotency?
After the cleavage, when differentiation starts.
When does the morula form?
When the zygote has 8-16 cells.
What is the compaction of the morula?
The cells start to adhere to each other via tight junctions & the morula fills up with fluid.
What does embryo genome activation do?
It means that development is a result of the embryo’s genome and no longer the mother’s genome.
What is ICM and what is its role?
ICM stands for Inner Cell Mass, it is made of smaller blastomeres. Its role is to differentiate into all the cells of our body.
What is the trophectoderm?
An outer layer composed of larger blastomeres.
What is the blastocoel?
A fluid-filled cavity in the embryo.
What is blastula hatching?
The rupture of the zona pellucida that allows the blastula to escape.
What causes blastula hatching?
Accumulation of water in the blastocoel + uterine. & embryonic enzymes.
Why does migration of embryo occur?
To allow embryos of polytocous species adequate space.
What stimulates embryo migration?
Oestrogen and prostaglandins stimulate uterine contractions which lead to embryo migration.
When do pig embryos migrate?
Between days 5-12
When do dog embryos migrate?
Between days 11-15
What is blastula elongation?
When the trophectoderm of the blastula gets very long & becomes filament shaped before implantation as a preparation for making the placenta.
What makes the placenta?
It occurs as a result of the interaction between the uterus & trophectoderm.
During embryo development, until when are cells totipotent?
Up to the morula stage.
During embryo development, until when are cells pluripotent?
The cells of the ICM
During embryo development, until when are cells multipotent?
The cells of the trophoblast
How can you get embryonic stem cells?
By isolating ICM cells.
How does twinning occur?
Either 2 embryos implant or ICM divides to form 2 embryos
What is the most common way that twins occur?
When the ICM divides
