Theoretical considerations on cell ensembles

Structure-function interdependency must apply at the supracellular level as well as at cellular and molecular levels. The overall structure and the intercellular geometry of the multicellular erythroblastic island, although strongly dependent upon molecular interactions (which determine or modulate recognition, adhesion, and the like), also carry consequences at a more general physical-chemical level. These relate to such factors as local concentrations and gradients, the nature of the forces and the phase-state of the material in the intercellular region, the generalized intercellular transport processes (diffusional, osmotic, electrokinetic, hydrodynamic, etc.), and the dynamic coupling of flows. Such "other-level" phenomena must play a significant role, and therefore must be taken into account, in formulating a comprehensive picture of the ways in which the microenvironment acts in the management and control of the processes of hematopoietic differentiation and development.