[Functional evaluation of cultured cells under hypotonic conditions by intravital staining with neutral red].

A high stability of pig embryo kidney-cells to hypotony was shown with neutral red vital staining. In the medium, diluted 1 : 1, the cells kept their ability to make granules during 6 days. In the medium diluted by water 1 : 3, both granular and diffuse staining of cells was shown within 6-12 hours. Later (18-48 hours) the cell ability to make granules was kept, but the neutral red was deposed as large vacuoles. In the normal medium the cell ability to make granules was kept too. In the medium, diluted by water 1 : 7, the cells lost their ability to make granules. The ability was recovered when cells were returned to the normal medium. Thus, after 6-18 hours of incubation in such a hypotonic medium, the cells produced small granules of neutral red, and 24-48 hours later they made large granules.