Assessing equine sperm-membrane integrity.

The swelling of cells in a hypo-osmotic medium has been described as an important criterion for assessing the functional integrity of the sperm plasma membrane. The resistance of equine spermatozoa to osmolarity changes was studied by extending 98 semen samples collected from nine stallions in media at five osmolarities (300, 200, 150, 100, and 50 mOsmol l(-1)). The response of the cells was measured by the spermatocrit technique and eosin staining. Spermatocrit determines the increase on spermatozoal volume under hypo-osmotic conditions, a sign of functional integrity of sperm plasma membrane, whereas the eosin staining evaluates the viability of spermatozoa. A significant positive correlation (P<0.01) was observed between spermatocrit values and percentage of eosin-unstained cells. Spermatocrit measurements and eosin staining proved to be useful methods to evaluate the integrity of sperm plasma membrane under hypo-osmotic conditions and could be used as an additional criterion to predict semen preservation ability.

Influencia da centrifugacao sobre a motilidade do semen de equinos em resistencia termica e congelamento. / Influence of centrifugation on equine semen motility in thermal resistance and freezing

Os resultados mostraram que a centrifugacao e um metodo adequado para o nivelamento da grande variacao dos ejaculados de equinos e que o aumento da forca de 1000xg para 2000xg nao apresenta nenhum efeito sobre a qualidade dos espermatozoides. Alem disso, o numero de espermatozoides que permaneceram no sobrenadante apos centrifugacao de 2000xg por 5 minutos foi pequeno e a perda consequentemente diminuida. A centrifugacao mostrou um efeito positivo na intensidade da motilidade dos espermatozoides, alem do que intensificacao nao depreciou a qualidade do semen "in vitro".Com relacao a motilidade e a coloracao supravital, melhores resultados foram obtidos com as centrifugacoes do que com o semen que nao foi centrifugado (congelado)