The ovule, also known as the megasporangium is the forerunner of the seed. It consists of a central mound of tissue called the nucellus, which is enveloped by one or two coverings - the integuments. An ovule ready for fertilization consists of nucellar tissue enveloped almost completely by integument(s), leaving a small pore or opening at the apical end.
This opening, called micropyle is the main passage for the entry of the pollen tube into the ovule. This end of the ovule is generally referred to as the micropylar pole and the opposite pole where funiculus is attached is called the chalazal pole. The ovule is attached to the placenta through a stalk-like structure the funiculus. In the nucellus is present the female gametophyte which is commonly referred to as the embryo sac.