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Fig. 5. Anterior defects in Xenopus embryos injected with 1.5 ng of xlr mRNA. (A) Uninjected tailbud stage embryos. (B) Weakly affected xlr injected embryo, note reduction in size of anterior structures. (C) Strongly affected xlr injected embryo, (D) Uninjected embryo showing xbf1 expression in the telencephalon and neural crest migrating into the branchial arches. (E) Weakly affected xlr injected embryo showing reduced xbf1 expression, indicating a reduced telencephalon. (F) Strongly affected xlr injected embryo with little xbf1 expression, indicating a dramatic reduction in the size of the telencephalon. (G) Uninjected embryo showing otxA expression in the forebrain and retina, and krox20 expression in rhombomeres 3 and 5 of the hindbrain. (H) Weakly affected xlr injected embryo showing reduced expression of otxA, indicating a reduction in the size of the forebrain and retina. Although two stripes of krox20 expression are evident, the gap between them is less distinct. (I) Strongly affected xlr injected embryo with greatly reduced otxA expression and a single krox20 stripe, indicating a dramatic reduction in the size of the forebrain, midbrain and hindbrain. (J) Uninjected embryo showing engrailed (en) expression at the midbrain-hindbrain boundary. (K) Weakly affected xlr injected embryo showing little affect on en expression. (L) Strongly affected xlr injected embryo with no en expression, indicating an absence of the midbrain and perhaps anterior portions of the hindbrain. The results suggest that injection of xlr mRNA causes severe reductions in anterior neural structures, including the forebrain, midbrain, and parts of the hindbrain. |
