Figure 3. Timeline of mRNA expression during lens development

Expression timeline of various cloned genes exhibiting an expression pattern within the presumptive lens ectoderm and the differentiating lens during development. Those in bolded blue represent the genes/clones described in this study, with identities, if any, which were determined. Those in black are genes that have been previously characterized in other studies [21,25,26,65-67,69-73]. The shaded regions of the bottom bars highlight key processes during lens development; Competence, which is initially achieved autonomously (AC; stages 10.5-12), is maintained throughout lens development once the presumptive lens ectoderm experiences lens-inductive interactions; Specification occurs at stage 19 at the transition between the early and late phases of induction; Commitment occurs at stage 26, when lens differentiation (placode formation) begins to takes place; stage 32 represents the time that the lens vesicle separates from the overlying head ectoderm. Expression of the all of the characterized genes (except tiarin) is maintained in the lens through at least stage 35. These data are an extension of that previously reported [25].