Difference Between Ovary and Ovule

The main difference between ovary and ovule is that the ovary is the organ that produces female gametes whereas the ovule is the structure inside the ovary of plants, which develops into female reproductive cells. Therefore, ovaries occur in both animals and plants while ovule only occurs in plants. In plants, ovary develops into the fruit while the ovule develops into seed after fertilization.

Ovary and ovule are two types of female reproductive structures of higher organisms.

Key Areas Covered

1. What is Ovary
     – Definition, Structure, Function
2. What is Ovule
     – Definition, Structure, Function
3. What are the Similarities Between Ovary and Ovule
     – Outline of Common Features
4. What is the Difference Between Ovary and Ovule
     – Comparison of Key Differences

Key Terms

Egg Cell, Fruit, Ovary, Ovule, Seed

What is Ovary

Ovary is an organ in the female reproductive system of both animals and plants, which produce the female gametes called eggs or ova. The ovaries in animals also secrete hormones, which coordinate various events of the sexual reproduction in females. The two main types of hormones secreted by the ovary are estrogen and progesterone. A female human body has a pair of ovaries on each side of the uterus. The size of a human ovary is similar to the size of a large grape. At birth, a female has 150,000 to 500,000 follicles per ovary that can develop into eggs. The release of an egg from an ovary occurs in a process called ovulation. Polycystic ovary syndrome (PCOS) is a disorder of the ovaries, which may lead to infertility in females.

Figure 1: Ovaries in Humans

In plants, ovary is a part of the pistil. It is located at the base of the petals. Ovules occur inside the ovary of plants. Following fertilization, the ovary develops into the fruit.

What is Ovule

An ovule is a structure found inside the ovary of plants. One to many ovules occurs in an ovary depending on the species. The ovule consists of three structural parts: integuments, nucellus, and embryo sac. Integuments are the two layers which cover the internal structures of the ovule. The small opening in the integuments is called the microphyl through which the pollen tube enters into the ovule. The nutrients required for the development of the embryo are stored in the nucellus.

Figure 2: Ovule Structure

A particular cell inside the nucellus develops into the megaspore mother cell, which is then divided by meiosis to produce four haploid cells. One of the four haploid cells develops into the megaspore. It becomes enlarged and undergoes four mitotic events to produce eight haploid cells. These are collectively called the embryo sac, which is also known as the megagametophyte. The embryo sac cell near the microphyl develops into the egg cell. Following fertilization, each ovule develops into a seed.

Similarities Between Ovary and Ovule

• Ovary and ovule are two types of female reproductive structures.
• Both can occur in the flower.

Difference Between Ovary and Ovule

Definition

Ovary refers to a female reproductive organ in which eggs are produced, present in humans and other vertebrates as a pair while ovule refers to the part of the ovary of seed plants that contains the female germ cell and after fertilization becomes the seed.

Occurrence

Ovary occurs in both animals and plants while ovule only occurs in plants.

Number

A pair of ovaries occurs in animals and a single ovary occurs per flower while one to more ovules occur inside the ovary of plants based on the species.

Function

The ovary produces and matures the female gametes while ovule develops into a female gamete in plants.

In Plants

Ovary turns into the fruit after fertilization while ovules turn into seeds.

Conclusion

The ovary is an organ in the female reproductive system, which produce egg cells. Further, ovaries occur in both animals and the flower of plants. In plants, ovule occurs inside the ovary of plants, which develops the seed following fertilization. The main difference between ovary and ovule is the correspondence of the structures and their function.

Reference:

1. Bradford, Alina. “Ovaries: Facts, Function & Disease.” LiveScience, Purch, 26 Apr. 2017, Available Here
2. “Ovule – Definition, Types, Components and Function.” Biology Dictionary, Biology Dictionary, 29 Apr. 2017, Available Here

Image Courtesy:

1. “Ovary nih” (Public Domain) via Commons Wikimedia 
2. “Embryosac-en” By Lokal_Profil (CC BY-SA 2.5) via Commons Wikimedia