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[Studies on the origin of various blood cell lines in the salamander Pleurodeles waltlii (author's transl)].

Grafting of haemopoietic organs was performed at several developmental stages between diploid and autotetraploid individuals of Pleurodeles waltlii. The difference in size between diploid and tetraploid cells is so obvious that their identification is possible by direct microscopic examination. To avoid immunological rejection, the grafts have been made with inbred animals. 2. After grafting the spleen, the host cells are observed to colonize it. This phenomenon is more important with spleens from donors at early stages of development. When the spleen from a late larval stage or a metamorphosed animal is transplanted into another larva, the blood of the latter contains 66 or 72% erythrocytes originating from the graft. 3. Embryonic liver grafting is followed by a colonization of all haemopoietic organs by cells originating from the granulopoietic tissue of the graft. The proportion of grafted blood cells is then very high. A liver graft performed at a larval stage gives qualitatively similar results but the numbers of cells originating from the graft are lower. A survey of intra-cardiac erythropoiesis in these animals shows that it develops from stream blood cells and not from cardiac endothelial cells. 4. After thymus graft, the lymphoid part of the organ is replaced by the host cells. 5. From these results, it is suggested that the granulopoietic liver tissue contains one or several kinds of stem cells which could differentiate into all types of blood cells.