Ultrastructure of carp Cyprinus carpio permatozoa after cooling, dilution and freeze-thawing.

Dilution of the carp spermatozoa with a cryoprotective medium was shown to inflict serious injuries to the fine structures of some spermatozoa. The amount of the injured spermatozoa increases after cryopreservation. Examination of the freeze-fracture micrographs of the heads of the carp spermatozoa, showed that their protoplasmic faces were covered with the particles in high concentrations. These particles do not form clusters after cooling the spermatozoa down to +5 degrees C and dilution with a cryoprotective medium. For the first time the authors observed the particles to form geometrically shaped regular formations on the outer membranes of the carp spermatozoa[pf1]. On the basis of the results obtained the authors propose that high susceptibility of the carp spermatozoa to osmotic exposures is apparently due to some particular features of the fine structures of their membranes and to their expected probably low heterogeneity.

Effect of cryopreservation on lipids and some physiological features of spermatozoa from rams pastured in highlands and in valleys.

The effect of low temperature preservation on the motility and morphology of acrosomes, acrosomal proteolytic activity, phospholipid and fatty acid composition of phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE), and the cholesterol/phospholipid molar ratio in sperm from rams housed in the highlands or in the valleys, were studied. The indices of motility and morphological integrity of sperm from highland rams were much greater compared with those of valley rams. Phosphatidyl choline (PC) of the highland rams was more unsaturated, while PE was more saturated compared with those of valley rams. Cryopreservation of the sperm from highland rams significantly increased the content of choline plasmalogen, accompanied by a slight rise in the levels of lysophosphatidyl choline (LPC) and phosphatidyl inositol (PI) in their sperm. The fatty acid composition altered following cryopreservation. These variations were mainly due to a decrease in the amount of docosahexaenic acid and an increase in the amounts of linoleic and palmitic fatty acids. The results may be indicative of the fact that the alterations in the sperm of the valley rams were more pronounced and they may be attributed to the structural features of the sperm, as well as a reduced concentration of oxygen in the organs and tissues of the highland rams.