The protein fibers in loose connective tissue are , , and reticulin.

The protein fibers in loose connective tissue are collagen, elastin, and reticulin.

1. Collagen: These are the most abundant fibers in the connective tissue. They are strong and flexible, and they provide resistance to stretching forces.

2. Elastin: These fibers are thinner than collagen fibers and they are stretchy. They allow the tissues to return to their original shape after being stretched or contracted.

3. Reticulin: These are the thinnest and shortest fibers. They form a network that supports cells and ground substance in many tissues. They are particularly abundant in soft organs like the liver and lymphatic system.