[Effect of diluents for long-term storage on the acrosomes of ram spermatozoa].

Samples of ram sperm, stored for a long time and diluted in a lactose-yolk or TRIS-glucose-yolk diluent in formulation currently used in A. I. practice in the Czech Socialist Republic, were subjected to morphological evaluation under optical and electron microscope. No visible differences between the diluents were observed under the optical microscope and the amount of acrosomal defects was just slightly higher than in the control fresh sperm. However, differences and changes were observed in the electron-microscopic pictures. When the former diluent was used, the percentage of acrosomal defects in the sperm stored for a long time was 44% and in the case of the latter diluent this percentage was as high as 59%, whereas in the control it was not higher than 16%. Most of the defects are caused during diluting and equilibration; less damage is suffered during freezing. The control osmometric determinations demonstrated a high hyperosmolality (495 mOsmol.kg-1) of the TRIS-glucose-yolk diluent. Hence the lactose-yolk diluent appears to be better, although the solubility of egg yolk in it is worse.