Structure of Ovule

Structure of Ovule:

The ovule is an integumented megasporangium found in spermatophytes which on fertilization with male gametes ripens into seed. An angiospermic ovule is typically an ovoid and whitish structure.

It is present inside the ovary and is borne over a parenchymatous cushion called Placenta. The stalk or the funiculus (also called funicle) is present at the base and it attaches the ovule to the placenta. The hilum is the point of attachment of the body of the ovule with the funiculus. It represents the junction between the ovule and the funicle.

Structure of a typical Ovule

A typical ovule is inverted or anatropous. Here, the funiculus is fused lengthwise with the ovule beyond the hilum. A ridge is formed called raphe. Funiculus is vascular (i.e. with xylem and phloem) to supply nourishment. The body of the ovule is made up of a central mass of parenchymatous tissue called nucellus which is surrounded by integuments. It encloses the embryo sac and provides nourishment to the developing embryo. Embryo Sac is the female gametophyte that contains the egg apparatus. Integuments are outer coverings of the ovule which provides protection to the developing embryo. The ovule with one or two integuments is said to be unitegmic or bitegmic ovules respectively. The integuments leave a narrow pore or passage at one end of the ovule. It is known as micropyle. The basal region of the body of the ovule where the nucellus, the integument and the funicle meet or merge is called chalaza.

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