Fate Maps of Neural Crest and Mesoderm in the Mammalian Eye

Abstract

The data provide essential new information toward understanding the complex interactions required for normal development and function of the mammalian eye. The results also underscore the importance of confirming neural crest and mesoderm fates in a model mammalian system. The complementary systems used in this study should be useful for studying the respective cell fates in other organ systems.

Spatial relations between avian craniofacial neural crest and paraxial mesoderm cells

“…Detailed mapping studies using quail-chick transplantations have defined neural crest cells as the exclusive source of connective tissue components in the entire midfacial, oral, and branchial regions of the head (LeLiévre and Le Douarin, 1975;Le Liévre, 1978;Noden, 1978Noden, , 1983aNoden, , 1988Couly et al, 1992Couly et al, , 1993Le Douarin et al, 1993;Köntges and Lumsden, 1996). Indeed, this process appears to be a common developmental theme in all vertebrates so far examined, including mice (Jiang et al, 2002;Matsuoka et al, 2005;O'Gorman, 2005;Gage et al, 2005). These properties have elevated the neural crest to the status of vertebrate synaptomorph (Gans and Northcutt, 1983;Kuratani, 2003;Santagati and Rijli, 2003;Northcutt, 2005).…”

“…This mesoderm is the sole source of skeletal muscles in the head and, together with lateral mesoderm, generates all craniofacial plus some cardiac endothelial precursors (Noden, 1983b(Noden, , 1986(Noden, , 1991aCouly et al, 1992Couly et al, , 1995. Extraocular and branchial muscles initiate their development within paraxial mesoderm, but complete their differentiation and morphogenesis at peripheral locations populated by neural crest cells (Noden, 1983b(Noden, , 1986Couly et al, 1992;Köntges and Lumsden, 1996;Matsuoka et al, 2005;Gage et al, 2005).…”

Molecular and developmental mechanisms of anterior segment dysgenesis

“…Key shows the colour coding used to represent the embryonic origin of the anterior segment tissues in the right-hand plates, and the pattern of expression of the Foxc1 and Pitx2 genes in the left-hand plates, based on published expression data. 40,42 anterior chamber is well defined (Figure 1b). Subsequent maturation of the angle tissue involves further tissue movement and differentiation; as the scleral spur develops it separates the ciliary body and iris root from the developing trabecular meshwork.…”

“…Similar fate mapping studies had not been carried out in the mouse or in any mammalian model until more recently. 40,41 In fact, it seems that there are significant differences in the contribution of cells to the anterior segment structures between mouse and chicks, and the human situation is probably closer to the mouse. In mouse, but not in chick, mesoderm-derived progenitors contribute to the anterior segment, particularly in the corneal stroma 40 (No.…”

“…40,42 It is striking that both genes are expressed very early in embryogenesis, equivalent to the first trimester of human development (Figure 1a). Both genes are not expressed in neural crest cells until they adopt a periocular location, hence they do not serve any function in regulating the migration of neural crest cells from the crest of the closing neural tube to the eye primordia.…”