The 4th day of the Training School (Thursday 16th of May) started with a conference by Dr. Vanesa Robles (Universidad de León, Spain), entitled “Analysis of cryopreserved material”, which was dedicated to review the different techniques for evaluation of the quality of different kinds of cells which can be frozen and guarantee their viability.
During the rest of the morning, a series of three shorter presentations, with the common title of “Cryopreservation in aquatic species: case studies” were given by Dr. Elsa Cabrita (ICMAN-CSIC), who talked about their experiments with grouper, Dr. Paz Herráez (Universidad de León, Spain), who explained their experiments in salmonids and Dr. Juan F. Asturiano (UPV, Spain), who focussed his talk to their works on cryopreservation of eel sperm.

In the afternoon, Dr. Elsa Cabrita and Dr. Marta Fernández Riesco conducted a practical session entitled “Cryopreservation of primordial and testicular germ cells”. Students extracted testis from sole specimens (donated by ICMAN-CSIC) and from European eel (donated by Valenciana de Acuicultura, S.L.).
Sole testicular tissue was diced and maintained in culture medium, according to the usual protocol for freezing for later extraction of spermatogonia. Once the process was finished, samples were distributed in cryotubes containing freezing medium, and they were frozen.