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 [...]
The changing appearance of the embryos, especially during organogenesis, invites the distinguishing of certain stages which can be referred to when it is desired to indicate how far an embryo has progressed in its development. Tables of "normal stages" have been worked out for a number of species of animals, especially those that are most often used for research. In [...]
In this article we will discuss about the selective affinities of cells as a determining factor in cellular rearrangements of an embryo. We may ask what is the nature of the forces which control the rearrangement of cells resulting from morphogenetic movements in gastrulation and also in other morphogenetic processes; we may ask whether the new positions of the cells [...]