[Physical mechanism of cell number self-regulation in a population]

It was shown that concentration of cells in a culture of Protozoa phylum (Infusoria) depends on cultivation volume. To explain the effect, a mechanism is proposed by which the maximum possible amount of cells in the culture is regulated. The mechanism is related to the density of radiation (electromagnetic or acoustic) flux emitted by cells. The radiation density increases with the cellularity in the cultivation volume and therefore can provide information on the total number of cells in the volume. The rations of cell concentrations in different volumes calculated under this assumption are in a good agreement with experimental data. It is proposed that a similar mechanism operates in the feed-back chain that regulates the cellularity in growing organs of multicellular organisms. It was concluded that, owing to this mechanism, mitoses during the growth of the organ would occur with increasing frequency at the periphery rather than in the center of the organ. Experimental evidence in support of this conclusion is presented.