NUCLEONS II: CRYOPRESERVATION AND METABOLIC ACTIVITY

The establishment of intracytoplasmatic sperm injection (ICSI) as a routine procedure in assisted fertilization has been used in the treatment of male infertility. The major technical problem that has arisen with the use of immotile sperm for ICSI has been differentiating between live and dead cells. Nucleons from human, pig, hamster, mouse, rat, and bull have been able to induce their chromatin decondensation by the action of heparin/GSH. Cryopreservation is deleterious to sperm function, killing more than 50% of the spermatozoa during the process. Nucleon cryostorage was performed at 5 and -5°C and analyzed for total area (µ2), perimeter (µ), width (µ), and length (µ), using Metamorph Imaging System software. On the other hand, fluorescein diacetate (FDA) is hydrolyzed by intracellular estereases to produce fluorescein, which exhibits green fluorescence when excited by blue light. This fact is a striking result since the presence of this metabolic activity opens the possibility to select the nucleons for ICSI. In the present study, the authors decided to search for a suitable metabolic test, which might reflect the metabolism and viability of these chromatin structures. This is a simple cryostorage technique that after months of cryopreservation, allow the use of nucleons for ICSI with suitable fertilization and pregnancies rates.