Distribution of laminins in the developing human eye

PURPOSE. To examine the distribution of laminin (Ln) chains in basement membranes (BMs) of the human cornea, lens, and retina in fetal development. METHODS. Ten fetal eyes (9-20 weeks of gestation [wg]) were serially sectioned and treated with specific antibodies against the Ln-alpha 1, -alpha 2, -alpha 3, -alpha 4, -alpha 5, -beta 1, -beta 2, -beta 3, and -gamma 1 chains. RESULTS. The BM of the corneal epithelium was reactive for Ln-alpha 3, -alpha 5, -beta 1, and beta 3 chains through all ages, whereas the Ln-alpha 1 chain was present at 9 to 12 wg and the Ln-alpha 4 chain from 10 wg. The Descemet's membrane (DM) was labeled with the Ln-alpha 1 and -a4 chains at 10 to 17 wg, the Ln-alpha 5 chain from 10 wg, the Ln-beta 1 chain at 11 to 17 wg, and the Ln-beta 3 chain from 17 wg. The Ln-alpha 1, alpha 5, -beta 1, and -beta 2 chains were present in the lens capsule and the internal limiting membrane (ILM) through all ages. The Bruch's membrane (BrM) was immunoreactive for the Ln-alpha 3, alpha 4, -alpha 5, -beta 1; and -beta 2 chains through all ages, whereas the Ln-alpha 1 chain was absent from 20 wg onward. The Ln-alpha 2 chain was not detected in the eye, but it was present in the extraocular muscles. CONCLUSIONS. BMs play an important role during morphogenesis, in that they influence cell proliferation, migration, and tissue differentiation. Lns are the major noncollagenous component of BMs. The presence of four different alpha chains, three beta chains, and one gamma chain of Ln in the eye reveals a high degree of complexity from the early stages of development and suggests an important role for the different Ln chains in human ocular differentiation.