During cooling of mammalian cells to subzero temperatures water tends to flow out of the cell to freeze externally and the cells shrink. If cooled too fast,  cells are injured by the formation of intracellular ice crystals, if cooled too slowly, cells will be injured by the  'solution effect',  i.e.,  by changes in the  composition  of  extra- and intracellular solutions during the ice formation.

In contrast to cell suspensions and tissue cultures,  cells  within a tissue matrix  are  subject to additional factors that may lead to fragmented DNA, fractures and cracks and exacerbate freezing injury.

Confocal LSM