Insemination of Frozen Semen

Cryoprotectants are added to the semen extender for spermatozoa to survive the freeze-thaw process. The most common cryoprotectants are:

Penetrating	Common Mechanisms of Action
glycerol	Act as both solvent and solute (just until equilibration). Replaces water as the solvent. Pass through cell membranes but less permeable than water Concentrations of solutes remain slow Have lower freezing point than water Cellular response to extender with glycerol:
DMSO
Non-penetrating	Common Mechanisms of Action
protein: milk, egg yolk	Act as solute Cannot enter cell Dehydrate the cell prior to freezing Cellular response to extender with lactose:
sugars: lactose, fructose, mannose, raffinose, trehalose
synthetic polymers: polyvinylpyrolidine, methyl cellulose