Development Chapter 8 Flashcards
Review of early development
1)Germinal cytoplasm forms in the vegetal pole of the uncleaved egg
2) Germ plasma becomes situated in the primordial germ cells of gut endoderm
3) Cells migrate to the genital ridges
4) Gonadal development occurs
5)Germs cell divide by mitosis and greatly increases in number
What is the vegetal pole
The yolk end of the embryo
What is the animal pole
The opposite end of the vegetal pole; contains mostly cytoplasm
What is a zygote
A fertilized cell
What are blastomeres
right after fertilization the cells that are made after the large amounts of volume of the ova is cleaved again.
What is Radial cleavage
The upper layer of cells sits directly atop the lower layer of cells
What is spiral cleavage
Cleavage which the planes are diagonal to the polar axis and unequal cells are produce by the alternate clockwise and counterclockwise cleavage around the axis of polarity
What is discoidal cleavage
In an early embryo cell division occurs within a small disc of cytoplasm atop a large mass of yolk
What is rotational cleavage
One of the two blastomere divides meridotally and the other divides equatorially
What are the two types of cleavage
Holoblastic cleavage and Meroblastic cleavage
How is holoblastic cleavage defined
It is defined by little yolk and the furrow goes all the way through the egg
how is meroblastic cleavage defined
It is defined by a lot of yolk and the furrow does not go all the way through the egg
How are Isolecithal eggs defined
Eggs that a little amount of yolk that is distributed evenly
How are Mesoelcithal eggs defined
Eggs that have an moderate amount of yolk; holoblastic
How are Telolecithal eggs defined
Eggs that have a lot of yolk; meroblastic
