11 July 1997
Vol 277, Issue 5323

About The Cover

A 24- to 26-hour zebrafish embryo (~2 millimeters long) whose left forebrain has been transformed into a section of the hindbrain, as indicated by the ectopic expression of a hindbrain-specific RNA marker (blue), in place of the eye. This posterior transformation of the cells is caused by a patterning signal from nonaxial mesendodermal precursor cells transplanted to the presumptive forebrain region at the shield stage. See 254. [Image: K. Woo and S. E. Fraser]