During lens development, which process forms secondary lens fibers postnatally?

• A. Posterior lens vesicle elongation to form primary lens fibers
• B. The anterior lens epithelium forms the epithelium and secondary fibers postnatally
• C. The anterior lens epithelium forms secondary lens fibers postnatally
• D. The corneal endothelium differentiates into lens tissue

Answer: (C)

Secondary lens fiber formation after birth arises from the anterior lens epithelium. In early development, the posterior cells of the lens vesicle elongate to create the primary lens fibers that form during embryogenesis. After birth, cells at the equator of the anterior lens epithelium exit the cell cycle and differentiate into elongated fiber cells that migrate toward the center, adding to the lens mass. This postnatal generation of secondary fibers from the anterior epithelium explains how the lens grows and maintains its transparency. The other ideas don’t fit: primary fibers come from the posterior vesicle during development, the epithelium isn’t newly formed postnatally to produce fibers, and the corneal endothelium does not become lens tissue.