Clonal Growth Versus Cell Mingling

Abstract

The variegated patterns seen in tissues of chimaeras and mosaics should tell us something about the developmental histories of these tissues. A number of ingenious approaches have been made to try to analyse these patterns, but there is still considerable controversy about the interpretation and relevance of this type of analysis (Mintz 1974; McLaren 1976; West 1978). Comparative analysis between different groups of animals or tissues, or between individuals of different ages, offers one of the more reliable approaches since this type of analysis is not dependent on precise numerical estimates. Even this approach, however, requires some caution and, in the past, a number of inappropriate comparisons have been made. It is essential to understand the contribution of the different elements to the total variegated pattern before a meaningful comparison can be made. The purpose of this article is to consider the organisation of variegated patterns seen in chimaeras and mosaics, and how the degrees of cell mixing and clonal growth in different groups of animals may be compared.