Aim: What happens after fertilization?
Do Now: Describe the process of fertilization.
A sperm enters an ovum, and the nuclei combine to form one with 46 chromosomes.
Sperm contacts the egg
Sperm or its nucleus enters the egg
Egg becomes activated and developmental changes begin
Sperm and egg nuclei fuse
Fuse- to physically join together
Ovum – egg cell (female gamete)
Cleavage – process of cell division during development
Differentiation – the process of forming different kinds of cells from similar cells of the early embryo
Embryo – an organism in an early stage of development
Morula – solid ball of cells formed from cleavage
Blastula – hollow ball of cells formed from cleavage
Gastrula – a hollow ball of cells with an “in pushing” and 3 layers (germ layers)
The Nuclei Fuse Together
Development of the zygote, the study of which is known as embryology or developmental biology.
The zygote undergoes a series of mitotic cell divisions called cleavage.
The stages of development are: Fertilized ovum (zygote) 2-cell stage 4-cell stage 8-cell stage Morula Blastula Early Gastrula Late Gastrula
Cleavage (divide via mitosis) forms the 2 cell stage
They split again to form the 4 cell stage
And again to form the 8 cell stage…
And eventually form a Morula
Next it becomes a blastula
And next, a gastrula
Sperm and ovum
Zygote (fertilized ovum)