**2. Origin and development of the Corneal Endothelium**

Neural crest cells, from which the CE is derived (Bahn et al., 1984; Johnston et al., 1979), migrate and differentiate in two waves during corneal development (Liu et al., 1998; Meier et al., 1982). In the first wave, the corneal epithelium is formed by periocular mesenchymal cells of neural crest origin and it synthesizes the primary stroma, after which neural crest cells migrate to the margin of the optic cup and then migrate between the lens and corneal epithelium to contribute to development of the CE and the trabecular meshwork. In the second wave, neural crest cells invade the primary stroma and differentiate into corneal keratocytes.
