Question

What is called filiform apparatus?

Answer 1

• Synergid cells are two specialized cells that lie adjacent to the egg cell in the female gametophyte of angiosperms and play an essential role in pollen tube guidance and function.
• The term synergid comes from the Greek “synergos,” which means “working together”.
• After a pollen grain germinates on the surface of the stigma, it forms a pollen tube that grows through the style and is guided through the micropyle (a minute opening at one end of the ovule).
• The pollen tube grows toward and into one of the synergid cells, which begins to degenerate as the pollen tube enters it (or shortly before).
• The pollen tube then ceases growth, ruptures, and releases its two sperm cells, which migrate to the egg and central cell, fertilization of which gives rise to the embryo and endosperm, respectively.
• The synergid cell wall forms a highly thickened structure called the filiform apparatus at the micropylar end, consisting of numerous finger-like projections into the synergid cytoplasm.
• This structure greatly increases the surface area of the plasma membrane in this region, which is also associated with an elaborated endoplasmic reticulum.