Question

Which are the innermost and the outermost parts of an ovule?

Answer 1

Ovule:

1. The ovule is the part of a female reproductive organ in seed plants, which contains a female gamete, and egg and gives rise to an embryo after fertilization.

Structure of the ovule:

1. The Ovule contains small stock that is the Funicle.
2. The Funicle is attached to the ovule by means of the Hilum.
3. The ovule is divided into three parts, outer integuments, middle nucellus, and innermost embryo sac as shown in the given diagram.

Integuments :

1. Integuments are the outer protective covering of the ovule.
2. There are two layers of integuments present in the ovule, outer integument, and inner integument.
3. There is a small opening at the top of the ovule in integuments known as Micropyle.
4. Opposite to Micropyle, Basal end, Chalaza is present.

Nucellus:

1. Inner to the integument, Nucellus is present.
2. It is a mass of cells, that provides nutrition to the embryo sac.

Embryo sac:

1. The innermost part of the ovule is the Embryo sac.
2. Megasporogenesis produces the embryo sac.
3. Seven cells and eight nucleated structures make up the embryo sac.
4. Three antipodal cells at the base, two synergids and one egg cell at the Micropylar end, and two polar nuclei at the center.