In semen banks, semen is preserved at low temperature using :

Ans. is c i.e. Liquid nitrogen Cryopreservation of semen : Involves cooling of embryos in the pronucleate stage or early cleavage stage to very low temperature in the presence of cryoprotectants such as : 12 - Propanediol (Iodine) - Glycerol - dimethyl sulphoxide (DMSO) with sucrose. They are then stored in liquid nitrogen till required.deg Over half the embryos survive thawing process. Oocyte preservation has not been successful. No adverse effects have been seen in babies born by this technique.