Structure of the Ovule: Funicle, Hilum, Integuments, Micropyle, Chalaza and Nucellus
Biology · Sexual Reproduction in Flowering Plants · NEET
The ovule is the megasporangium of a flowering plant. It hangs from the placenta by a stalk called the funicle; the funicle joins the ovule body at the hilum. One or two integuments cover the ovule and leave a small opening, the micropyle, at the top. The basal region is the chalaza, and inside is a mass of cells called the nucellus that holds the embryo sac (female gametophyte). Memory hook: outside-to-inside from the top down = "Micropyle first, Nucellus and embryo sac inside, Chalaza at the base."
Longitudinal section of an ovule: funicle attaches it to the placenta at the hilum; integuments cover the nucellus and leave the micropyle at the apex; the chalaza is the base and the embryo sac lies within the nucellus.
Your doubts, answered
Is the ovule the same as the megasporangium?
Yes. NCERT states the ovule is technically the megasporangium. Ovules arise from the placenta of the ovary. Do not confuse it with the megaspore mother cell or megaspore, which are cells found inside the ovule, not the ovule itself.
What is the difference between the hilum and the micropyle?
The hilum is the junction where the body of the ovule fuses with the funicle (the stalk). The micropyle is a small opening at the top of the ovule, left by the integuments. Hilum is a basal attachment point; micropyle is an apical entry point through which the pollen tube usually enters.
What is the nucellus and why is it important?
The nucellus is a mass of cells inside the ovule, enclosed by the integuments. It has abundant reserve food and houses the embryo sac (female gametophyte). In some seeds, such as black pepper and beet, part of the nucellus persists and is called the perisperm.
Where exactly is the embryo sac located?
The embryo sac (female gametophyte) lies inside the nucellus of the ovule. An ovule generally has a single embryo sac formed from a megaspore. So the order from outside is: integument, then nucellus, then embryo sac.
How do funicle, hilum and chalaza differ?
The funicle is the stalk that attaches the ovule to the placenta. The hilum is the region where the ovule body fuses with the funicle. The chalaza is the basal part of the ovule body, lying opposite the micropylar end. Funicle = stalk, hilum = joint, chalaza = base.
How many integuments cover an ovule?
An ovule may have one or two protective envelopes called integuments. They enclose the nucellus except at the tip, where they leave the small opening called the micropyle.
⚠️ The NEET trap ✗ The ovule is equivalent to the megaspore mother cell or the megaspore. ✓ The ovule is technically the megasporangium. The megaspore mother cell and the megaspore are cells located inside the ovule, not the ovule itself. 🧠 Ovule = megasporangium (a whole organ); the megaspore is just one cell inside it.
Real NEET questions
NEET 2016
The ovule of an angiosperm is technically equivalent to
A · Megasporangium ✓
B · Megasporophyll
C · Megaspore mother cell
D · Megaspore
Solution: The ovule of an angiosperm is technically the megasporangium; NCERT explicitly equates the two ('Arising from the placenta are the megasporangia, commonly called ovules'). The megaspore mother cell and megaspore are cells inside the ovule, and the megasporophyll is the carpel bearing ovules, not the ovule itself.
NEET 2020
The body of the ovule is fused within the funicle at
A · Nucellus
B · Chalaza
C · Hilum ✓
D · Micropyle
Solution: The ovule is attached to the placenta by a stalk, the funicle. The region where the body of the ovule fuses with the funicle is the hilum, the junction between ovule and funicle. Nucellus is the central tissue, chalaza is the basal part, and micropyle is the apical opening.
NEET 2019
Persistent nucellus in the seed is known as
A · Chalaza
B · Perisperm ✓
C · Hilum
D · Tegmen
Solution: When remnants of the nucellus persist into the mature seed, this residual persistent nucellus is called the perisperm (e.g., black pepper, beet). Chalaza is the ovule base, hilum is the ovule-funicle junction, and tegmen is the inner seed coat.
Solved Sexual Reproduction in Flowering Plants NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
An ovule is a small structure inside the ovary that develops into a seed after fertilisation. It is technically the megasporangium and contains the embryo sac.
What does the micropyle do?
The micropyle is a small opening at the top of the ovule. It is usually the point through which the pollen tube enters the ovule during fertilisation.
What is the chalaza?
The chalaza is the basal part of the ovule, lying at the end opposite to the micropyle. It is the region from which the integuments and nucellus originate.
What is the difference between the ovule and the seed?
The ovule is the structure before fertilisation. After fertilisation, the ovule matures into the seed and the ovary develops into the fruit.
Why is the ovule called the megasporangium?
Because meiosis inside the ovule produces megaspores. A structure that produces megaspores is a megasporangium, and NCERT directly equates the ovule with it.
