The physical structure in animals that is similar to the physical structure in plants that produces pollen is the testes.
Just as plants produce pollen in specialized structures called anthers, male animals produce sperm in specialized structures called testes. Both anthers and testes are reproductive structures that produce gametes (pollen grains and sperm cells, respectively) that are necessary for sexual reproduction in plants and animals.
Feathers and scales are integumentary structures that serve different functions such as insulation, protection, and sensory perception, and are not involved in reproduction. The skeleton is a supportive structure that provides a framework for the body and protects internal organs, but it does not produce gametes.