Question

Function of filiform apparatus is to
(a) Recognize the Suitable pollen at the stigma
(b) Stimulate division of the generative cell
(c) Produce nectar
(d) Guide the entry of pollen tube

Answer 1

Hint: The synergies take place through its filiform apparatus which is a finger-like structure at the base of synergids. Pollen tube entry into the embryo sac where pollen tube enters the embryo sac only through the micropylar pore. The synergid from which pollen has entered starts degenerating.

Complete step by step answer:
- At the micropylar pole, the synergid cell wall is thickened and extensively invaginated, forming a structure called the filiform apparatus.
- The filiform apparatus greatly increases the surface area of the plasma membrane in this region and contains a high concentration of secretory organelles, suggesting that it may facilitate the transport of substances inside and out of the synergid cells.
- Thus the filiform apparatus has at least two functions associated with the fertilization process.
First, the synergid cells secrete pollen tube attractants with the help of the filiform apparatus.
Second, the pollen tube enters the synergid cell by growing through the filiform apparatus.

So, the correct answer is, ‘Guide the entry of pollen tube.’

Additional Information:
- Filiform apparatus seems to be formed mainly from substances transformed from starch grains.
- Structurally, a filiform apparatus has a core of tightly packed microfibrils enclosed by a non- fibrillar sheath. It resembles a spongy wall of transfer cells. Rich in polysaccharides.
- Filiform apparatus plays a role in directing pollen tube growth to the synergid cell. One of the synergids forms a seat for pollen tube discharge in the embryo sac.
- Filiform apparatus may be aiding the synergid in absorption and transportation of materials into embryo sac from the nucleus. filiform apparatus forms a path of entry for these substances.
- The surface area of the plasma membrane at micropylar end increased by filiform apparatus, and cytoplasm near filiform apparatus rich in secretory organelles( ER, dictyosomes, vesicles) – is suggested that filiform apparatus facilitates the transport of substances into and out of synergid.
- According to on cytological staining properties in species other than Arabidopsis, the filiform apparatus appears to be composed of a number of substances including cellulose, hemicellulose, pectin, callose, and protein.
- Pollen tube entry into ovule, it is of three types:
Chalazogamy: In which pollen tube enters the integuments of ovule through the chalazal end.
Porogamy: In which pollen tube enters the ovule through the micropylar opening.
Mesogamy: In which pollen tube enters the ovule by piercing the integuments in the middle of the ovule, between chalaza and micropyle.
- The male gamete is brought to the egg by a pollen tube; the phenomenon is known as Siphanogamy.
- Fertilisation occurs in 4 main stages:
Germination of pollen tube on stigma.
Growth of Pollen tube.
Pollen tube entry into the embryo sac.
The fusion of Gametes.


- Filiform apparatus differentiation from synergid wall described by Habermann.
- Electron microscope revealed filiform apparatus is a mass of finger- like projections into the synergid cytoplasm.
- Many scientists suggested that the filiform apparatus doesn’t play a role in nutrition because of the presence of cuticles over the micropylar wall of embryo sac.