FIG. 1.

Chimera formation between medaka blastomeres and zebrafish embryos. (A and A') Micrograph of a 3-day-old embryo of medaka strain HB32C, showing black-pigmented melanophores (A) and autofluorescent guanophores (asterisks; A'). (B and B') Micrograph of a 3-day-old zebrafish embryo, showing black pigmentation in the eye (B) and the absence of autofluorescent cells (B'). (C) Micrograph of 2-day-old chimeric embryos, showing medaka blastomere-derived autofluorescing guanophores (asterisks) in zebrafish hosts. (E–I) Micrographs of a chimeric fry at 5 days postfertilization (dpf), showing the presence of 2 clusters of guanophores in the trunk (asterisk) and dorsal head surface (frame) of the chimera (E). The medaka guanophores (arrows) are yellow and brown in color under bright field optics (F), and are positive for yellow (G), green (H), and red fluorescence (I) under fluorescent optics. (J–L) Merged micrographs of a posthatching chimeric fry at 5 dpf, showing guanophores in the eye (circle). Color images available online at www.liebertonline.com/scd