Ova Development in Oviparous Animals
In the oviparous animals (all birds, most fishes, amphibians and reptiles) the ova develop protective layers and pass through the oviduct to the outside of the body. They are fertilized by male sperm either inside the female body (as in birds), or outside (as in many fishes). After fertilization, an embryo develops, nourished by nutrients contained in the egg. It then hatches from the egg, outside the mother's body. See egg (biology) for a discussion of eggs of oviparous animals.
The egg cell's cytoplasm and mitochondria (and chloroplasts in plants) are the sole means the egg is able to reproduce by mitosis and eventually form a blastocyst after fertilization.
Read more about this topic: Ovum
Famous quotes containing the words ova, development and/or animals:
“The whole tree itself is but one leaf, and rivers are still vaster leaves whose pulp is intervening earth, and towns and cities are the ova of insects in their axils.”
—Henry David Thoreau (1817–1862)
“For the child whose impulsiveness is indulged, who retains his primitive-discharge mechanisms, is not only an ill-behaved child but a child whose intellectual development is slowed down. No matter how well he is endowed intellectually, if direct action and immediate gratification are the guiding principles of his behavior, there will be less incentive to develop the higher mental processes, to reason, to employ the imagination creatively. . . .”
—Selma H. Fraiberg (20th century)
“From the oyster to the eagle, from the swine to the tiger, all animals are to be found in men and each of them exists in some man, sometimes several at the time. Animals are nothing but the portrayal of our virtues and vices made manifest to our eyes, the visible reflections of our souls. God displays them to us to give us food for thought.”
—Victor Hugo (1802–1885)