Page 101 - Science Class 08

This techinque was first successfully introduced on the eggs to provide sufficient heat to the
in humans in 1978 and is called invitro eggs. When the chick is completely developed,
fer lisa on (IVF). it bursts the egg shell.

Development of Embryo

You have studied that zygote is formed in the
oviduct a er the fer lisa on. The zygote
divides repeatedly to give rise to a ball of cells.
The cells then begin to form groups that
develop into different ssues and organs of the
body. This developing structure is called
embryo. The embryo gets embedded in the Internal Fer lisa on in Hens
walls of the uterus for further development.
Thus, fer lisa on takes place inside the body of
The embryo gradually develops body parts
the hen, but the embryo develops outside its
such as hands, legs, head, eyes, ears, etc. The
body.
stage of the embryo in which the body parts of
the unborn baby can be iden fied is called a Viviparous and Oviparous Animals
fetus. When the fetus develops into a complete You already know that some animals give birth
baby the mother gives birth to it. to their young ones while some animals lay eggs
which develop into young ones. The animals
which give birth to their young ones are called
viviparous animals. On the other hand, the

animals which lay eggs are called oviparous
animals. You should remember that birds,
amphibians, fishes, insects and rep les lay eggs.

Development of Embryo
Internal Fer lisa on in Hens A. Make a list of viviparous and oviparous.

Internal fer lisa on also takes place inside the Viviparous Oviparaous
body of female birds. Let us take the example
of hen.

A er fer lisa on, the zygote divides repeatedly
and travels down the oviduct. While traveling
down, many protec ve layers are formed B. Answer the following ques ons.
around it. Gradually, these protec ve layers 1. What is asexual reproduc on?
takes the form of hard shell. 2. How can a single parent
reproduce?
A er the hard shell is formed around the
3. How do hydra reproduce?
embryo, the hen finally lays the egg. It takes
about 3 weeks to develop the embryo into a 4. What is binary fission?
5. What is budding?
chick. During this period, the hen regularly sit

Science-8 101