Page 3 - Reproduction in Animals

female gametes called ova (eggs)
(Fig. 6.4). In human beings, a single
matured egg is released into the oviduct
by one of the ovaries every month.
Uterus is the part where development of
the baby takes place. Like the sperm,
an egg is also a single cell.
Nucleus
Fig. 6.4 : Human Ovum
Boojho recalls that the size
of eggs in animals varies.
The egg may be very small
as in humans, much larger
as in hens. Ostrich egg is
the largest!
Fertilisation
The first step in the process of
reproduction is the fusion of a sperm
and an ovum. When sperms come in
contact with an egg, one of the sperms
may fuse with the egg. Such fusion of
the egg and the sperm is called
fertilisation (Fig. 6.5). During
fertilisation, the nuclei of the sperm and
the egg fuse to form a single nucleus.
This results in the formation of a
fertilised egg or zygote (Fig. 6.6). Did
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Rationalised-2023-24
Sperms
Ovum
Fig. 6.5 : Fertilisation
you know that the zygote is the
beginning of a new individual?
Fusing
nuclei
Fig. 6.6 : Zygote
The process of fertilisation is the
meeting of an egg cell from the mother
and a sperm cell from the father. So,
the new individual inherits some
characteristics from the mother and
some from the father. Look at your
brother or sister. See if you can recognise
some characters in them similar to those
of your mother or your father.
Fertilisation which takes place inside
the female body is called internal
fertilisation. Internal fertilisation
occurs in many animals including
humans, cows, dogs and hens.
SCIENCE