Revision Flashcards
What are primordial germ cells?
Precursor (partly differentiated) cells in the early embyro which represent the germ line and will produce germ cells
What is the difference between a blastocyst and a blastula?
Blastula is a hollow ball of cells with a fluid filled balstocel on the insid
- Blastocyst in mammals, has an inner cell mass
What determines the position of the inner cell mass?
Sperm entry
What is the trophoblast of a blastocyst?
- Outer layer (trophoectoderm), outside of the inner cell mass
- Gives rise to the placenta and chorion (the extraembryonic tissue)
What is the zona pellucida?
Completely surrounds the whole blastocyst, the egg hatches out of here before implantation
What is the primitive streak?
Where the ectoderm invaginates in a mammal
What is a morula?
A solid ball of cells which give rise to blastocyst in a mammalian embyro
What are blastomeres?
The cells deriving from cleavage in a blastula or blastocyst
When do eggs complete meiosis?
After fertiliastion, but this occurs differently in different species
What pattern of cleavage do humans undergo?
Holoblastic
What pattern of cleavage does the fish and chick undergo?
Meroblastic
What does endoderm give rise to?
- Gut
- Pancreas
- Liver
- Pharynx
- Trachea
- Lungs
What does the mesoderm give rise to?
- Heart
- Blood
- Kidney
- Muscle
- Bone
- Dermis
What does the ectoderm give rise to?
- Nervous system (neural crest)
- Placodes
- Epidermis
What happens during morphogenesis?
Gastrulation and neurulation
