2. Embryonic development is when the embryo is formed and
develops.
It starts with the fertilization of a egg , which after is
called a zygote.
The zygote goes through rapid divisions
Process is known as embryogenesis
4. • The single celled zygote undergoes a period of rapid cell division
without growth to produce a ball of cells.
5.
6. • A hollow ball of cells are formed called a blastula.
• The blastula consist of many smaller cells called blastomeres.
• The blastula has a hollow part that is filled with fluid and is called
a blastocoel.
7. 1) Meroblastic cleavage
incomplete division of the egg.
occurs in species with yolk-rich eggs
only part of the zygote undergoes cleavage
happens in eggs due to the large volume of yolk
2) Holoblastic cleavage
complete division of the egg.
occurs in species eggs have small amount of yolk
entire zygote undergoes cleavage
8. Early embryonic development in which the cells of a
blastula rearranges into a three-layered embryo, called
a gastrula.
9.
10. Pander(1817): Trilaminar condition of chick
balstoderm.
Primary germ layers:
only ectoderm & endoderm ( Radiata).
only germ layers in primitive metazoan
stage.
Secondary germ layers:
third layer( mesoderm) is also present.
( Bilateria , Triploblastica ).
11. Series of organised integrated process that transform
an amorphous mass of cells into complete organ
from the germ layers
12.
13.
14. Developmental biology-7th edition-Scott F.
Gilbert
A manual of Developmental biology-
Vijayakumaran Nair.