Filiform apparatus is

Options

A. thick layer at micropylar end
B. thin layer at micropylar end
C. thick layer at chalazal end
D. thin layer at chalazal end

Answer

### Step-by-Step Solution:

1. **Definition of Filiform Apparatus**: The filiform apparatus is a specialized structure found at the micropylar end of the embryo sac in flowering plants (angiosperms).

2. **Location**: It is located at the micropylar end of the embryo sac, which is the part of the ovule that faces the pollen tube during fertilization.

3. **Function**: The primary function of the filiform apparatus is to guide the pollen tube towards the egg cell. The pollen tube carries two sperm cells, and the filiform apparatus helps direct these sperm cells to the appropriate location for fertilization.

4. **Structure**: The filiform apparatus consists of specialized cells called synergids, which have a unique cellular thickening. This thickening aids in the guidance of the pollen tube.

5. **Role in Fertilization**: When the pollen tube reaches the embryo sac, the filiform apparatus plays a crucial role in ensuring that the pollen tube penetrates the synergids and facilitates the entry of sperm cells into the egg cell and the central cell (for double fertilization).

### Summary:
The filiform apparatus is a crucial structure in the fertilization process of flowering plants, located at the micropylar end of the embryo sac, guiding the pollen tube to ensure successful fertilization.

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