Fig. 7

Abnormal morphology of the optic primordia and ectopic expression of pax6 and pax2 genes in the proximal anterior neural plate in kny^m119 tri^m209 embryos during the formation of a cyclopic eye. (A, B) Nomarski images of live embryos at the 16-somite stage. In wild-type embryos (A) two separate eye placodes are seen (ey), and the prospective telencephalon (t) and diencephalon (d) are positioned between the eyes at the anterior edge of the neural keel (arrow). In kny^m119 tri^m209 mutant embryos (B) one continuous eye placode (ey) is observed with the prospective telencephalon and diencephalon positioned posterior and dorsal to the forming eye. (C, D) pax6 and (E, F) pax2 expression visualized by whole-mount in situ hybridization. pax6 expression in wild-type embryos (C) is detected in distal regions of the anterior neural plate in the future diencephalon and eyes and is absent from the median region of the anterior neural plate (arrow). kny^m119 tri^m209 double mutants have ectopic pax6 expression in the median region of the neural keel (arrow), while expression in the prospective diencephalon is compressed and located posterior to the eye field. pax2 in wild type is expressed in two optic stalks (os) separated by the midline; in contrast, one continuous domain is observed in kny^m119 tri^m209 double mutants with ectopic expression in the median region of the anterior neural keel (arrow).