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ovoviviparity

n. The condition of being ovoviviparous.

Wikipedia
Ovoviviparity

Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos that develop inside eggs remain in the mother's body until they are ready to hatch. This method of reproduction is similar to viviparity, but the embryos have no placental connection with the mother and receive their nourishment from a yolk sac. In some species, this is supplemented by uterine secretions or other maternal provisioning.

The young of ovoviviparous amphibians are sometimes born as larvae, and undergo metamorphosis outside the body of the mother, and in some insect species, such as the tachinid flies, the embryos develop to the first larval instar stage before they are laid and the eggs hatch almost immediately.