Embryonic development begins with fertilization forming a zygote, which undergoes rapid cell division through cleavage. This forms a hollow ball of cells called a blastula. The blastula then undergoes gastrulation where the cells rearrange into three germ layers - ectoderm, endoderm, and mesoderm. Organogenesis then transforms these germ layers into complete organs through a series of organized processes.

1. Presented by
Aswathy A
Akshaya Anil
S 3 M.Sc Biochemistry
Dept.of Biochemistry
Kerala University

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

3. 1) Cleavage
2) Gastrulation
3) Organogenesis

4. • The single celled zygote undergoes a period of rapid cell division
without growth to produce a ball of cells.

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.

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

14.  Developmental biology-7th edition-Scott F.
Gilbert
 A manual of Developmental biology-
Vijayakumaran Nair.