title: Lymphocyte differentiation and allograft reactivity. Experimental studies on the origin of thymic lymphocytes.
abstract: The generalization that the developing vertebrate thymus is colonized by circulating stem cells that originate in the yolk sac blood islands is questionable. The view that the yolk sac is the primary source of thymic lymphocytes is based largely on inferences drawn from experimental protocols that are highly artificial.
mesh_terms: D000818:Animals; D001001:Anura; D002454:Cell Differentiation; D002678:Chimera; D008214:Lymphocytes / Q000166:cytology*; D013950:Thymus Gland / Q000276:immunology / Q000637:transplantation; D014184:Transplantation, Homologous