A large-scale, orthogonal network of microfibril bundles in the corneal stroma

Orthogonal and parallel arrays of microfibril bundles are described in the corneal stroma of embryonic and adult chickens. The arrays lie parallel to the corneal surface and are distributed in the extracellular matrix between Bowman's layer and Descemet's membrane. The individual microfibril bundles measure 0.1-0.25 micron in diameter and consist of 20-30 "tubular" rods, of approximately 15 nm diameter, and an apparently structureless matrix. The arrays have a spacing of approximately 3 microns. We speculate that the microfibril bundles serve as a scaffolding for the corneal stroma or as a light-diffracting element. With some variations in distribution and organization, the arrays of microfibril bundles also occur in calf, rabbit, rat, newborn mice, toad, and goldfish, but not in adult human corneas.