Intro to animal development - lecture 8 Flashcards
What is the ball of cells called after fertilisation has occurred?
Blastula stage embryo
What does Xenopus blastula look like?
Dark pigmented animal pole and egg rich vegetal pole
Which parts of the blastula divide quicker?
The blastomeres (cells of animal pole) divide faster than the yolk cells
What is the radical cleavage?
Alternating angle divisions. Cells get smaller and smaller , no growth just division
What is the grey Crescent?
When the sperm enters there is a 30 degree rotation, which exposes a wedge of cytoplasm producing a lighter coloured ‘grey Crescent’
what does the grey crescent respond to in the future?
The dorsal/ back of the embryo
What does the sperm entry respond to In future development?
The ventral/belly side
What is Gastrulation?
Invagination of cells to generate 3 germ layers; the endoderm , mesoderm and the ectoderm
What is the archenteron?
The primitive gut, invades the blastocoel
What happens to the blastoel during gastrulation?
It decreases in size
What is the epiboly in gastrulation
Movement of cells in which a cap of cells form epithelial monolayer on top of the embryo
What is the gastrulation stage?
Beginning of formation of the interior embryo , causes tissues to fold inward. The site where the cells migrate is called the blastopore . The grey crescent makes up the Dorsal lip
What is the neural tube formed of?
Ectoderm
Which animals were the first cloning experiments done?
Amphibians
What is the neural plate stage?
embryo after gastrulation
what happens during Neurulation?
Raised neural folds appear either side of a neural groove on a neural plate, the folds move together to from a closed neural tube
Somatic cell nuclear transplantation
- DNA from pigmented frog egg destroyed
- cell removed from albino blastula embryo , nucleus removed
- Nucleus put into the ‘host’ egg
- albino frog
Can differentiated adult cells be used in cloning?
yes
When was Dolly the sheep cloned?
Roslin institue , 1997
what are the three key lessons we can learn from animal cloning?
- DNA can be reprogrammed to allow development following differentiation
- DNA is not lost during development
- gene expression must be regulated
What is the dorsal lip?
just below the grey
crescent , Where cell movements start
what does the Ectoderm form?
The nervous system
what does the mesoderm form?
- muscles , bone, cartilage, connective tissue, organ tissue and blood
What does the endoderm form?
epithelial cells of digestive and respiratory tubes
