Question

What is inside of pollen?

Answer 1

A pollen grain is a microscopic body that contains the male reproductive cell of a plant.

Explanation:

Pollen grains harbour the haploid microgametophytes of seed plants (spermatophytes) that deliver twin sperm cells to the female gametophyte via the pollen tube.
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There are three main components of a pollen grain. The inside of the grain is made up of cytoplasm. This fluid medium houses the aforementioned living cells, keeping them moist and alive.

Detailed description and graphics here:
http://study.com/academy/lesson/pollen-grain-definition-structure-function.html