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)
“The American has dwindled into an Odd Fellow—one who may be known by the development of his organ of gregariousness.”
—Henry David Thoreau (1817–1862)
“Shall we never have done with that cliché, so stupid that it could only be human, about the sympathy of animals for man when he is unhappy? Animals love happiness almost as much as we do. A fit of crying disturbs them, they’ll sometimes imitate sobbing, and for a moment they’ll reflect our sadness. But they flee unhappiness as they flee fever, and I believe that in the long run they are capable of boycotting it.”
—Colette [Sidonie Gabrielle Colette] (1873–1954)