Finfish Breeding and Hatchery Management (2+1)

Unit 17 - Cryopreservation of fish gametes

17.3. Cryopreservation of eggs/embryos

• Attempts to cryopreserve fish eggs and embryos have been met with little or no success.
• The fundamental problems are – insufficient dehydration during cooling/freezing due to relatively large size (1-6 mm) of fish eggs, the presence of membranes of different water permeability.
• Also permeation of cryoprotectant even into smaller eggs and embryos is low.
• However, success has been achieved with invertebrate eggs and embryos.
• Sea urchin embryos, oyster larvae (trochophore) and penaied shrimp naupli have been successfully cryopreserved and revived.

Embryonic cell cryopreservation

• Studies show that the cells from blastula can be removed and successfully cryopreserved.
• This involves dechorionization of unfertilized water-hardened egg, removal of nucleus from the egg, micro-injection of thawed dissociated cells from mid-blastula into the enucleated egg and its subsequent development into a viable embryo.

A matur Egg (oocyte)