Differentiation is a term that is somewhat ambiguous, as it is used at least in two senses – a broader, more general sense and a narrower sense. In the broad sense, differentiation is the process in which the cells or other parts of an organism become different from one another and also different from their previous condition. For example, while [...]
In experiments of disaggregation and re-aggregation of embryonic cells, there sometimes arise complexes in which differently differentiated tissues are present in chaotic arrangement, having no relation, or only a slight relation, to the arrangement of the same tissues in a normal individual. We have referred to such complexes as teratomas (Fig. 454). The term "teratoma," however, was originally coined to [...]
In this article, the changing pattern of processes of differentiation will be shown in examples taken from the development of living organisms. Hemoglobins: How specific genes change their activity during development is illustrated by the composition of hemoglobins in man. The hemoglobin in adult humans is in the form of composite molecules consisting of four units (polypeptides), two of which [...]