Effect of Sperm Cryopreservation on the European Eel Sperm Viability and Spermatozoa Morphology

The main objective of the present work was to study the effect of cryopreservation of European eel sperm both on the sperm viability and the spermatozoa head morphology. Spermatozoa morphology was evaluated with computer-assisted morphology analysis after collection in fresh samples, after adding the freezing medium containing dimethyl sulfoxide as cryoprotectant and, finally, after the cryopreservation process and thawing. Cell viability was assessed, in both fresh and thawed samples, by Hoechst 33258 staining. Computer-assisted sperm analysis (CASA) was used to determine the percentage of motile cells and to measure motility parameters in sperm samples. A significant decrease of head perimeter (12.56%) and area (17.90%) was detected from spermatozoa in fresh to thawed samples, indicating that cells do not recover the original size after the cryopreservation process. CASA was used to measure the percentage of motile cells (51.9%) and spermatozoa motility parameters such as curvilinear, straight line and angular path velocities, as well as beating cross frequency. This technique was employed in the fresh sperm samples but proteins present at the freezing medium (L-alpha-phosphatidylcholine) made impossible to use this last technique in thawed samples. When sperm viability was assessed by Hoechst staining, a significant decrease of approximately 15% (73.10 vs 58.26%) of alive spermatozoa was registered from fresh to thawed samples. The percentage of motile cells measured by CASA in fresh samples (51.9%) was lower than the percentage of alive cells determined by Hoechst stainning, suggesting the existence of different batches of spermatozoa in different stages of development, even during the eight to tenth weeks of treatment, when the highest sperm quality was found.     

Glasser's Disease of Swine Produced by the Intratracheal Inoculation of Haemophilus suis

The intracheal inoculation of pigs with Haemophilus suis led to the production of Glasser's disease at every attempt without significant pulmonary involvement. Isolation of this organism from the experimental animals was possible only in the acute phase of the disease.

The indirect fluorescent antibody technique when applied to frozen sections of tissues obtained from the experimentally infected pigs at autopsy, revealed a few rod forms but mostly “round bodies” of H. suis in animals from which the organism was isolated, and “round bodies” only in the pigs from which the organism was not isolated.

Attention is drawn to the similarities between the lesions caused by H. suis and Mycoplasma hyorhinis, and to the confusion which may result therefrom. It is stressed that the laboratory diagnosis of these two diseases is complicated by the fact that both agents may not be isolated on the media commonly used in diagnostic laboratories. Both organisms necessitate the use of special media where the clinical and autopsy results indicate polyserositis and arthritis.