Figure 8. Dynamics of periocular neural crest (pNC) response to the extracellular matrix (ECM) in the context of the expression of nephronectin (Npnt) and fibronectin (Fn) during corneal development.

(A) Cross-section of embryonic day (E)5 eye immunostained for Npnt and Fn. Npnt appears in an increasing gradient from the periocular region into the cornea, whereas Fn stains both the periocular mesenchyme and cornea. (B) All pNC respond to Fn via expression of α5β1, but a subpopulation of pNC that reside in the region adjacent to the presumptive cornea express both α5β1 and α8β1, and become competent to also read the additional gradient of Npnt in the ECM, thus migrating into the corneal region. oc, optic cup; ps, primary stroma; en, corneal endothelium.