Clonal origin of haematopoietic colonies in the postnatal mouse liver

Abstract

The liver of the neonatal mouse continues to show haematopoietic activity for up to 2 weeks after birth^1,2 and morphological analysis has shown that this activity becomes focused in discrete haematopoietic colonies by the end of the first week postnatal³. Furthermore, each colony contains cells of one haematopoietic lineage only, that is, erythroid, myeloid or pre-B-lymphoid cells. This pattern of differentiation suggests that each colony is derived from a single committed precursor cell, which, if true, would represent the first demonstration of non-mixed haematopoietic colonies in normal development and would provide a useful system for studying the factors affecting the clonal diversity of haematopoietic stem cells and their lineage-committed progeny. Here we have analysed the haematopoietic foci in the liver of neonatal mouse chimaeras, using a newly developed ubiquitous in situ cell marker system which clearly demonstrates the clonal origin of these colonies.