Organ-specific alterations of ultrastructure and morphofunctional condition in different organism's tissues, which could evidence of the genetic factors inclusion under the development of different hypoxic condition in organism, were investigated. The dates obtained indicated the marked organ-specific "structure" reaction of tissues, cells and organelles under various exogenous influences. Such reactions confirm the presence of different genes expression which account for ultrastructure alterations; its activity is determined by a type, intensity, duration of influence as well as organ belonging. Ultrastructural alterations are mainly determined by tissue and cell factors but not by genetically determined system reactions; it is confirmed by various reactions on external factors in animal tissues with different genetically determined oxygen consumption level or genetically determined adaptation to middle-altitude conditions.