In birds and reptiles only .
See the related Wikipaedia link for detailed information.
Yes that is possible, it has happened twice to me!
A fertilized egg that develops inside the female's uterus is called an embryo. During this stage, the embryo undergoes cell division and differentiation, eventually forming the various tissues and organs of a developing organism.
The bird embryo develops inside the protective shell of the egg, using the egg yolk as a source of energy and materials from which it will develop.
The egg is made with the embryo inside the body but the duckling inside the egg develops outside the ducks body.
In the egg, and if the species gives birth to live young, in the egg which rests inside the mother's body.
In mammals, the embryo develops with in the specialised part of the oviduct .
the developing embryo is nourished by yolk
The embryo develops from a fertilized egg, which is formed when a sperm fertilizes an egg cell during sexual reproduction. The fertilized egg undergoes cell division and differentiation to form the various tissues and organs of the developing embryo.
In a way, you could say "both inside and outside". The egg is produced and fertilized inside the mother. She lays the egg and incubates it so the embryo grows outside the mother and develops into the hatchling hummingbird.
Embryo is formed in germinal spot of yolk .
No, chicken eggs do not have a heartbeat. The embryo inside the egg develops a heartbeat only after a few days of incubation.