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Updated: Jul 27, 2025
Dechorionation of Medaka Embryos and Cell Transplantation for the Generation of Chimeras
Published on: December 22, 2010
Pigmentation Patterns of Mouse Chimaeras following Injection of Embryonic Cells into Postimplantation Embryos In
Yuji Kajiwara1, Takashi Kuwana2, Minoru Inouye1
1Pathology Section, National Institute for Minamata Disease, Minamata, Kumamoto 867.
Chimaeric mice were produced by introducing dissociated embryonic cells of C57BL/6N mice into the embryos of Jcl: ICR albino mice at mid-gestation in utero. The patterns and the existence of pigmented areas were investigated over the long term. The pigmentation of the chimaeras was observed in several locational patterns; mainly in the head and the breast, rarely in the tail, the abdomen, the anterior and posterior trunk. During long-term observation, the pigmentation became faint in 6 of 7 chimaeras and completely disappeared in 2 of 7 chimaeras 6 months after birth, as was true in our previous observation in rat/mouse chimaeras. The reason for this discoloration, however, is unknown at present; melanocytes derived from donor cells may have failed to function or have been eliminated. To examine the entry routes of injected cells into the embryos, pollen particles, similar to embronic cells in size, were injected as a donor material. The particles were localized mainly on the mid-dorsal line in the head, and breast near fore-limb buds 48 hr after injection. These patterns were similar to those of areas where the pigmentation were observed in the chimaeras. The results suggested that the cells were passively incorporated into embryos on the dorsal midline and the abdomen through the neural tube and somatopleure closure, respectively.
Chimaeric mice were produced by introducing dissociated embryonic cells of C57BL/6N mice into the embryos of Jcl: ICR albino mice at mid-gestation in utero. The patterns and the existence of pigmented areas were investigated over the long term. The pigmentation of the chimaeras was observed in several locational patterns; mainly in the head and the breast, rarely in the tail, the abdomen, the anterior and posterior trunk. During long-term observation, the pigmentation became faint in 6 of 7 chimaeras and completely disappeared in 2 of 7 chimaeras 6 months after birth, as was true in our previous observation in rat/mouse chimaeras. The reason for this discoloration, however, is unknown at present; melanocytes derived from donor cells may have failed to function or have been eliminated. To examine the entry routes of injected cells into the embryos, pollen particles, similar to embronic cells in size, were injected as a donor material. The particles were localized mainly on the mid-dorsal line in the head, and breast near fore-limb buds 48 hr after injection. These patterns were similar to those of areas where the pigmentation were observed in the chimaeras. The results suggested that the cells were passively incorporated into embryos on the dorsal midline and the abdomen through the neural tube and somatopleure closure, respectively.
