An ovule (megasporangium) generally has a single embryo sac formed from a megaspore through reduction division. It is a small structure attached to the placenta by means of a stalk called funicle.
Ovule $\rightarrow$ Megaspore Mother Cell (MMC) by meiosis $\rightarrow$ Megaspore
Each has one or two protective ervelopes called integuments. Nucellus is a mass of cells enclosed with the integuments. Fruits develop from the ovary of flower, ather floral parts degenerate and fall off.