Final answer:
The predominant type of collagen for connective tissue (CT) and periodontal ligament (PDL) fibers is Type I collagen, which provides strength and resistance to stretching, and is secreted by fibroblasts in connective tissue.
Step-by-step explanation:
The type of collagen that is predominant for connective tissue (CT) and periodontal ligament (PDL) fibers is typically Type I collagen.
Connective tissues include various types with different functions, such as dense connective tissue which has a high concentration of collagen fibers providing great tensile strength and resistance to stretching.
Fibroblasts are the most abundant cells in connective tissue proper, secreting collagen and other proteins that form the extracellular matrix.
The periodontal ligament is a specialized connective tissue that surrounds the roots of teeth and helps attach the tooth to the bone.
The collagen fibers here are arranged in a manner that supports the tooth, withstands the mechanical forces during mastication, and preserves the integrity of the periodontal space.