Question

Cryopreservation is used for the preservation of

• A. Fish eggs
• B. Fish milt
• C. Fish embryos
• D. Both fish egg and milt

Hint:

Fish Cryopreservation Facts: Cryopreservation in Liquid Nitrogen ($-196^\circ\text{C}$) is successfully established for FISH MILT (Sperm). NOT feasible for fish eggs/embryos due to massive yolk volume and impermeable chorion.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Cryobiology and genetic resource banking in teleost fishes: liquid nitrogen cryopreservation (-196°C) is routinely successful for flagellated spermatozoa (milt), whereas large yolk volume, multicell membranes, and low membrane water permeability prevent successful cryopreservation of intact fish eggs or embryos.
Key Formula or Approach:
\[ \text{Cryopreservation in Liquid Nitrogen } (-196^\circ\text{C}) \implies \text{Routinely Successful for } \mathbf{Fish \text{ } Milt} \]

Step 2: Detailed Explanation:
In fish cryobiology and aquatic germplasm preservation:
1. Fish Milt (Spermatozoa) (B): Small, compact cells ($< 5\;\mu\text{m}$) with high surface-to-volume ratio, low water content, and high membrane permeability to cryoprotectants (DMSO, methanol, glycerol). Cryopreservation of fish milt in liquid nitrogen ($-196^\circ ext{C}$) is a mature, highly successful technology routinely practiced for ex situ genetic conservation and hatchery breeding.
2. Fish Eggs and Embryos: Extremely large size ($1 - 5\text{ mm}$), massive yolk volume, low surface area-to-volume ratio, and an impermeable chorion prevent uniform cryoprotectant penetration and vitrification, resulting in lethal intracellular ice crystal formation. Intact fish eggs/embryos cannot be successfully cryopreserved using current technologies.

Step 3: Final Answer:
Thus, cryopreservation is used for the preservation of Fish milt, matching option (B).