Quantitative Histology of Spleen Colonies in Irradiated Mice

Abstract

S ummary . Quantitative histological examinations were carried out on large numbers of spleen nodules obtained in heavily irradiated mice by injection of bone‐marrow and foetal liver cell suspensions. Endogenous colonies and clones arising from irradiated bone‐marrow cells have also been analysed. It was found that the large majority of clones consisted of cells of either erythroid or myeloid or mega‐karyocytic type. A smaller percentage of clones were mixed with association of the various cell types in all possible combinations. Statistical analysis of the data revealed consistent differences in the distribution of clones derived from various sources. Attention is particularly focused on the mixed clones with a discussion of their significance in the light of the mono‐ or poly‐phyletic origin of blood cells.