The document summarizes key stages in chick embryo development: 1) Fertilization occurs internally in the oviduct and the egg acquires protective coverings as it passes through the reproductive tract. 2) For development to continue, the egg must be incubated at temperatures between 36-38 degrees Celsius, either by the mother or in an artificial incubator. 3) After fertilization, rapid cell division (cleavage) occurs, forming a disc of cells (blastoderm) on the yolk's surface that will develop into the embryo. 4) Cleavage results in a spherical cluster of cells (morula) that then forms a fluid-filled cavity (blastocoel) to become a blast

1. Chick Embryo
Development
8th dec

2. •It is the basic scheme of development
and help understand the complex and
difficult process of development in
different animals easily.
•It is fundamental process which is
common in all animals.

3. •FERTILIZATION AND INCUBATION:
•The chick egg (called yolk) is surrounded
by various accessory coverings secreted
by female reproductive tract.
•Fertilization is internal and takes place
when ovum or egg enters into oviduct.
•The shell is secreted as egg pass through
shell gland(uterus).

4. •Temperature of egg:
•When the egg is laid if the
temperature of egg does not matches
with the body of mother the process
of development stops and only
continues again if mother sits on it’s
eggs to incubate them

5. •Artificial Incubation:
•In eggs artificially incubated, the
incubators are usually regulated at
temp b/w 36-38c.
•At this temperature, the chick
completes development and is
hatched on the 21st day.

6. •Cleavage:
•Immediately, after fertilization, the egg
undergoes a series of mitotic division
called Cleavage.
•Discoidal cleavage: In bird’s egg cleavage
is only confined to small disc of
protoplasm lying on suface of YOLK on
animal pole.

7. • The cleavage furrows start in clear cytoplasmic
region.
•PLANES OF CLEAVAGE:
•The first two cleavages occur in vertical
manner.
•Third cleavage occurs in horizontal
plane.
•The successive(next) cleavages are
irregular and number of cells increases.

8. Zygote 1st cleavage 2nd cleavage 3rd cleavage 4th cleavage 5th cleavage

9. •MORULLA:
•Cleavage results in formation of rounded
closely packed mass of blastomeres.
•It is called morula and consist of disc
shaped mass of cells two or more layers
in thickness (blastoderm) lying close to
yolk.
•In the center of the blastoderm the cells
smaller and completely defined while at
periphery are flattened and elongated.

11. •Blastula:
• The morula stage is short-lived and soon changes
into blastula is characterized by the presence of a
segmentation cavity or blastocoel.
• The discoidal cap of cells above the blastocoel is
called Blastoderm.
• The marginal area of blastoderm in which the cells
remain undetached from the yolk and closely
adherent to it is called the Zone Of Junction.
Area of Attachment