The ovule is a key structure in flowering plants that develops into a seed after fertilization. Understanding the parts of the ovule and their specific roles is essential for NEET biology, CBSE board exams, and general plant anatomy studies.
This article provides a complete guide to:
- The structure of ovule in angiosperms
- Functions of each part like funicle, hilum, micropyle, chalaza, and more
- Diagrams, tables, and NEET-style facts
What is an Ovule?
An ovule is a small, oval-shaped structure present inside the ovary of flowering plants. It is attached to the placenta of the ovary and develops into a seed after fertilization.
Each ovule contains the female gametophyte (embryo sac), which houses the egg cell for reproduction.
Parts of the Ovule and Their Functions
1. 🔺 Ovule
- Basic unit of seed formation
- Attached to the placenta
- Contains all parts that support fertilization and seed development
2. 🔺 Funicle
- A stalk-like structure that connects the ovule to the ovary wall (placenta)
- Transports nutrients from the plant to the ovule
🧠Think of it as the umbilical cord of the ovule.
3. 🔺 Hilum
- The point of attachment between the ovule and the funicle
- Appears as a scar on the seed after fertilization
📌 Important for water and nutrient exchange
4. 🔺 Integuments
- Protective envelopes that surround the ovule
- Typically two layers in angiosperms: outer and inner integuments
- Leave a small gap called the micropyle
📘 Post-fertilization, integuments form the seed coat
5. 🔺 Micropyle
- A tiny pore at the tip of the ovule between integuments
- Allows entry of the pollen tube during fertilization
🧬 After fertilization, micropyle becomes the entry point for water and oxygen in the seed
6. 🔺 Chalaza
- The basal region of the ovule, opposite to micropyle
- Site where integuments and nucellus join
- Helps in nutrient transport from the parent plant to embryo sac
7. 🔺 Nucellus (2n)
- A mass of diploid (2n) parenchymatous cells
- Enclosed by integuments
- Provides nutrition to the developing embryo sac
🧠Abundant nucellus is a sign of food-rich seeds (e.g., in endospermic seeds)
Summary Table: Parts of Ovule and Functions
| Part | Function |
|---|---|
| Ovule | Becomes the seed after fertilization |
| Funicle | Attaches ovule to placenta |
| Hilum | Junction of funicle and ovule; nutrient exchange |
| Integuments | Protective coverings; form seed coat |
| Micropyle | Entry point for pollen tube |
| Chalaza | Base of ovule; transport site for nutrients |
| Nucellus | Nutritive tissue; surrounds embryo sac |
Importance of Ovule in Reproduction
Site of meiosis and megaspore formation- One egg cell
- Two synergids
- Three antipodals
- Two polar nuclei
NEET & Board Exam Focus
Questions related to ovule parts frequently appear as:
- Diagram labeling
- One-liner definitions
- Function-based MCQs
Example NEET MCQ:
Q: Which part of the ovule allows the entry of pollen tube?
A. Hilum
B. Nucellus
C. Micropyle ✅
D. Chalaza
FAQs on Ovule Structure
Q1. What is the function of integuments?
A1. They protect the embryo sac and form the seed coat post-fertilization.Q2. Where does double fertilization occur?
A2. Inside the embryo sac within the ovule.Q3. What is the hilum?
A3. It is the junction between the ovule and the funicle.Q4. Which ovule part remains visible on mature seeds?
A4. Hilum and micropyle can often be seen on seeds.
