AD1 Flashcards
What is morphogenesis?
Mechanism of body shape formation
In a blastodisc what are the epiblast and hypoblast?
Epiblast= embryo Hypoblast= extraembryonic membranes
What are the 4 extraembryonic membranes that support the embryo in bird eggs?
1) Yolk sac- nutrient transfer
2) Amniotic sac- protection
3) Chorion- gas/water exchange
4) Allanois- waste storage
What are the 4 key stages of development?
1) Fertilisation
2) Cleavage
3) Gastrulation
4) Organogenisis
5)
What is in the animal and vegetal hemispheres?
Animal- nucleus of the egg
Vegetal- nutrients
What is cleavage? And what is the name of each separate cell?
Diffusion of cells to form a blastula (hollow ball of cells)
Each separate cell is called a blastomere
What happens at determination and differentiation?
Determination- cells fate become fixed
Differentiation- cells become structurally and functionally specialised
What is oranogenesis?
The formation of organs and organ systems
What is neuralation?
The formation of the nervous system in vertebrates
What does fertilisation initiate?
The rapid division producing multicellular embryo
Where does the cytoplasm and mitochondria of a zygote come from?
The egg
Describe cortical rotation and what the gray crescent controls?
Cortical rotation- Sperm enters at the animal hemisphere, the cortex then rotates exposing the gray crescent
Gray Crescent- Protiens inside control what form the cells will take
What is gastrulation?
Formation of tissue layers and axis
What are the 3 effects of mitotic spindles on cleavage patterns?
1) Radial cleavage- spindles form at right angles or parallel to axis
2) Spiral cleavage- spindles are oblique angles to axis
3) Rotational cleavage- first division is parallel, second division is at right angles
What are the 2 stages of body segmentation?
1) Somites- produce vertebrae, ribs and muscles
2) Neural crest cells- produce peripheral nerves
What are the 3 types of cleavage? and what is the effect of yolk on cleavage pattern?
1) Complete cleavage
2) Discoidal incomplete cleavage
3) Superficial incomplete cleavage
1) Cells divide asymmetrically
2) Cleavage furrows dont penetrate the yolk- blastoclyc forms
3) Nuclei migrate to the edge and are ? into individual cells
