Changes of the internal organization of the plasma membrane correlated to the regeneration potency of the cell

Internal organization of the plasma-membrane of rat thymocytes and pituitary tumor cells (GH₃) was experimentally altered by low temperature and either changing osmolarity or adding drugs destroying the cytoskeleton. These treatments induce reversible aggregation of intramembrane particles of the plasma membrane. Thin section electron microscopy of the hypotonically shocked cells show all the cell organelles to be extremely swollen and the cytoplasmic space to be rather empty. Returned to physiological conditions, the cells show normal morphological aspects, accompanied by ‘normal’ permeability properties of the plasma membrane; the aggregation of intramembrane particles is reversed. The proliferation behaviour of GH₃-cells is not affected by this treatment. This demonstrates a high regeneration potency of the mammalian cell and leads to the assumption that molecular components which are important for the survival of the cell must be structural (membrane) bound.