Egg Apparatus, Synergids and the Filiform Apparatus
Biology · Sexual Reproduction in Flowering Plants · NEET
The egg apparatus sits at the micropylar (top) end of the embryo sac and has three cells: two synergids and one egg cell. The synergids carry a special thickening called the filiform apparatus, which guides the pollen tube into the embryo sac. Memory hook: "Egg is the boss, two synergids are the guards, and the guards hold a GPS (filiform apparatus) that shows the pollen tube the door."
The egg apparatus (2 synergids + 1 egg cell) lies at the micropylar end. The filiform apparatus on the synergids guides the incoming pollen tube. The 2 polar nuclei are in the central cell and the 3 antipodals sit at the chalazal end.
Your doubts, answered
Is the filiform apparatus part of the egg cell or the synergids?
It is part of the synergids, not the egg. The filiform apparatus is a special cellular thickening at the micropylar tip of the two synergids. NEET often tries to trick you by saying the egg has a filiform apparatus. That is wrong. Only the synergids have it, and it guides the pollen tube into the synergid.
How many cells are in the egg apparatus?
Three cells. The egg apparatus is made of two synergids plus one egg cell. All three lie together at the micropylar (top) end of the embryo sac. Do not add the polar nuclei here; they are in the central cell, not in the egg apparatus.
What is the exact function of synergids?
Synergids have two jobs for NEET. First, their filiform apparatus guides the pollen tube into the embryo sac. Second, the pollen tube enters one synergid and releases the two male gametes into its cytoplasm. So the synergid is the delivery site, but no male gamete fuses with the synergid itself.
Does the egg apparatus contain the polar nuclei?
No. This is a very common exam trap. The egg apparatus has only two synergids and one egg cell. The two polar nuclei sit in the large central cell, below the egg apparatus. In NEET 2025 this exact mistake was tested as a false Reason statement.
Where exactly is the egg apparatus located in the embryo sac?
At the micropylar end (the end near the micropyle, the pollen tube entry point). The three antipodal cells lie at the opposite chalazal end, and the large central cell with two polar nuclei is in the middle. This top-versus-bottom placement is frequently asked.
Do the male gametes fuse with the synergids?
No. The pollen tube releases both male gametes into a synergid, but the synergid only receives them. One male gamete then moves to the egg (syngamy) and the other moves to the polar nuclei in the central cell (triple fusion). The synergid stays haploid and does not take part in any fusion.
⚠️ The NEET trap ✗ The egg has a filiform apparatus, or the egg apparatus contains the two polar nuclei. ✓ The filiform apparatus belongs to the two synergids (not the egg), and the egg apparatus has only two synergids and one egg cell. The two polar nuclei are in the central cell. 🧠 Filiform = synergid feature; Egg apparatus = 3 cells (2 synergids + 1 egg), never the polar nuclei.
Real NEET questions
NEET 2016 Phase 2
In majority of angiosperms
A · Egg has a filiform apparatus
B · There are numerous antipodal cells
C · Reduction division occurs in the megaspore ✓
D · A small central cell is present in the embryo sac
Solution: By elimination this is the only acceptable choice. The filiform apparatus belongs to the synergids, not the egg, so option A is wrong. Antipodals are only three, not numerous, so B is wrong. The central cell is large, not small, so D is wrong. The intended answer is C, since reductional (meiotic) division gives rise to the megaspores from the megaspore mother cell.
ReNEET 2026
Which of the following in the female gametophyte of an angiosperm helps in guiding the pollen tube for fertilizing the eggs?
A · Antipodals
B · Synergids ✓
C · Central cells
D · Polar nucleus
Solution: The two synergids at the micropylar end carry the filiform apparatus, a special cellular thickening that guides the pollen tube into the embryo sac. Antipodals, the central cell and the polar nuclei do not have this role, so the answer is Synergids.
NEET 2025
Assertion (A): A typical unfertilized, angiosperm embryo sac at maturity is 8 nucleate and 7-celled. Reason (R): The egg apparatus has 2 polar nuclei. Choose the correct answer.
A · A is true but R is false ✓
B · A is false but R is true
C · Both A and R are true and R is the correct explanation of A
D · Both A and R are true but R is not the correct explanation of A
Solution: The Assertion is true: after the 8-nucleate stage, six nuclei become cells and two remain as polar nuclei in the central cell, giving an 8-nucleate but 7-celled embryo sac. The Reason is false because the egg apparatus is made of two synergids and one egg cell only; the two polar nuclei lie in the large central cell, not in the egg apparatus. So A is true but R is false.
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.
Two synergids and one egg cell. Together they form the egg apparatus at the micropylar end of the embryo sac.
What is the filiform apparatus and what does it do?
It is a special cellular thickening at the micropylar tip of the synergids. It guides the pollen tube into the synergid, helping fertilisation happen.
Is the egg cell haploid or diploid?
The egg cell is haploid (n). After it fuses with a male gamete during syngamy, it forms the diploid (2n) zygote.
Why is the egg apparatus placed at the micropylar end?
Because the pollen tube enters through the micropyle. Placing the synergids and egg near the entry point lets the filiform apparatus guide the tube straight to the gametes.
Do synergids fuse with the male gametes?
No. The pollen tube releases both male gametes into a synergid, but the gametes then move on. One fuses with the egg and the other with the polar nuclei. Synergids stay haploid and do not fuse.
