Ovule or Megasporangia

The Plant is a type of plant. The ovule is a component of the female reproductive organ that is responsible for fertilisation. It is the portion of the plant where female reproductive cells are produced and maintained, and it is these cells that, after fertilisation, grow into seeds. Later on, these seeds ripen and develop into mature plants. Flowers have ovules stored in ovaries at the very bottom of a vase-like structure known as a carpel, which has a neck, or style, and a hole at the top, or stigma, that allows pollen to pass through.

After fertilisation, the ovule in a flower begins to grow, and as the process of forming a seed progresses, the ovule begins to toughen up. The ovary begins to grow around it and eventually develops into a fruit. However, this is not always the case with plants. The ovules in plants such as avocado are only one, whereas the ovules in kiwi are numerous and can mature into fruits. When it comes to angiosperms, the ovaries are found inside the egg, however when it comes to gymnosperms, the ovules are found on the female cones.

Ovules components.

The ovule of a plant has a variety of distinct components, each of which serves a specific function. The Nucellus, Integuments, and the female Gametophyte are the components that make up this structure.

Nucellus: 

The nucellus is the largest component of the ovule, and it contains the embryo sac as well as the nutritive tissue of the ovule. Despite the fact that the plants have been fertilised, this nutritive tissue remains in place and feeds nutrients to the embryo. It can be located at the centre of the flowering plant’s flowering stem.

Integuments: 

This is the strong protective coat that surrounds the ovule during development. Because it is an ovule, it serves to safeguard the seeds. This integument completely encloses the nucleus, but it leaves a small gap known as the micropyle. Most of the time, there is only one integument in an ovule in gymnosperms, but angiosperms have two integuments in each of their flowers. Within the ovule, the integument is comprised of gamete-producing sexual organs, which are essential for the reproduction of all plants. This haploid female gametophyte, also known as the embryo sac or megagametophyte, is distinguished by the presence of only one unpaired chromosome, indicating that it is a haploid female.

Ovules variety of shapes and sizes.

In a plant, there are six different types of ovules, and these different types of ovules are distinguished by their forms.

• Chalaza is the place where the nucellus and integuments come together, and it can be either orthotropous or atropous. A plant ovule that is orthotropous is one that has its body lined up straight so that the chalaza, the funicle (which is responsible for attaching the ovule of the plant to the placenta), and the micropyle are all aligned.

• The hilum is a scar that indicates the location where the seed was eventually attached to the fruit by the funicle. It is seen in anatropous plants. Anatropous ovules are totally inverted during development, resulting in a micropyle that is located close to the hilum of the ovule.

• Hemi-Anatropous: In this case, the ovules are arranged at a right angle to the funicle, forming a right triangle. Its form finally takes on the appearance of an ovule laying on its side.

• It is believed that the Campylotropous embryo sac is slightly curved as a result of the ovule’s bent shape and the loss of alignment between the chalaza and micropyle that happens in Campylotropous.

• In the case of the Amphitropous ovule, the body is bent in such a way that the ovule and embryo sac take the shape of a horseshoe when they are combined.

• This is the most distinct of the circinotropous shapes since it has the most distinct shape. In the case of the circinotropous ovule, the funicle is so long that it forms a complete circle around the ovule, with the micropyle pointing upwards at the end of it. In comparison to the other six varieties of ovules, it is considered to be the most distinctively formed.

The Ovule Variety of Functions

The Ovule of the Plant is a reproductive organ that is critical in the reproduction of sexually reproducing plants. With the existence of an ovule, the process of reproduction becomes much more straightforward. When a pollen grain lands on the stigma of a flower of the same species as the pollen grain, the plant produces a pollen tube that travels down through the style of the flower. Following that, the pollen tube travels through the ovary until it reaches the ovule of the plant, at which point fertilisation can take place because the nucleus of the pollen grain is sent down to unite with the nucleus of the embryo sac.

Conclusion

In plant reproductive organs, an ovule is a female reproductive organ that contains an egg cell that, after fertilisation, develops into a seed. In angiosperms, ovules develop within the ovary, whereas in gymnosperms, ovules are connected to the inner surface of the female cone, and ovules develop inside the ovary in angiosperms. In gymnosperms, the ovules are completely unprotected, whereas in angiosperms, the ovules are protected by a structure called the megasporophyll. Angiosperm ovules are composed of several layers of protective tissue, integuments, and an embryo sac after they have matured.