title: Freezing injuries in the embryos of Piaractus mesopotamicus.
abstract: Cryopreservation of mammal embryos has been technically feasible for many years, but morphological injuries still persist in fish embryos during cryopreservation. Thus, the objective of the present study was to describe these freezing injuries in Piaractus mesopotamicus embryos. Two hundred and twenty-five embryos were collected at the post-gastrula stage and assigned into four treatments of sucrose at 8.5, 17.0, 25.0 or 34.0% plus 9.0% methanol. The control was prepared with distilled water only. The gradual decrease in the temperature was 0.5°C/min. After the seeding stage, the fish embryos were stored in liquid nitrogen at -33°C. Thereafter, they were thawed for evaluating per cent hatching, and the samples collected from every treatment were submitted to scanning electron microscopy for morphological analysis. The micrographic images showed that there was substantial alterations in embryo morphology under the highest concentrations of sucrose. These solutions did not prevent the formation of ice crystals, which lead to deformities and killed the embryos, but the observed reduced level of morphological structure in these embryos when treated with 17.0% sucrose plus 9.0% methanol is a compelling argument for additional studies.
authors: Departamento Zootecnia, Universidade Federal do Rio Grande do Sul (UFRGS), Maringá, Paraná, Brasil. darci.peixegen@gmail.com
authors: Darci Carlos
authors: DC
authors: Fornari
authors: Ricardo Pereira
authors: RP
authors: Ribeiro
authors: Danilo Pedro
authors: DP
authors: Streit
authors: Lauro
authors: L
authors: Vargas
authors: Nelson M Lopera
authors: NM
authors: Barrero
authors: Gentil Vanini
authors: GV
authors: de Moraes
mesh_terms: D000818:Animals; D060126:Characidae; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents; D004625:Embryo, Nonmammalian / Q000648:ultrastructure*; D005615:Freezing; D008855:Microscopy, Electron, Scanning; D013395:Sucrose / Q000494:pharmacology
chemical_list: D003451:Cryoprotective Agents; D013395:Sucrose