Semen quality in relation to semen preservation

A goal of research in laboratory evaluation of semen has been ultimately to predict the fertility achievable with use of that semen. This would permit evaluation of the male and ejaculate. For artificial insemination, semen viability becomes a measure of man's interaction with that semen in an effort to preserve its functional life. Man's efficiency in developing successful methods of semen preservation are, therefore, contingent upon the relationship of tests of semen quality and fertility. Problems discussed are those associated with identification of the most appropriate tests of spermatozoan viability important to fertility. These problems reside predominantly in poor repeatability of many tests (objectivity versus subjectivity), the interaction of semen quality and quantity in the inseminate, the effect of latent cell injury encountered in some systems of preservation (example frozen semen), and identification of viability traits of spermatozoa important to their retention and transport in the female reproductive tract as well as their ability to fertilize the egg and sustain embryogenesis. A case is established for the use of more than one viability test or semen trait for evaluating systems of semen preservation.

Oxygen consumption rate as a measurement of freeze-induced damage to chicken spermatozoa

The present study was conducted to determine if oxygen consumption rate of postthaw spermatozoa could be used as the indicator of freeze-induced damage. Pooled semen was diluted fourfold with 5.7% glucose solution containing various levels of glycerol or N-methylformamide for freezing by the pelleting method. Sperm motility and oxygen consumption rate were determined after thawing the samples at 37 C. 1) The maximum motility and oxygen consumption rate of postthaw spermatozoa were observed at 10 and 7% glycerol, respectively. However, no significant differences existed among semen samples diluted in 7, 10, and 15% glycerol. 2) The motility and oxygen consumption rate of spermatozoa frozen with 6 to 9% of N-methylformamide were higher than those of spermatozoa frozen with 0, 3, 12, or 15%. 3) A highly significant positive correlation was observed between motility and oxygen consumption rate immediately after thawing and also after 10 min incubation at 20 C with either cryoprotectant. 4) The polarographic measurement of oxygen consumption rate of postthaw spermatozoa appeared to be a reliable method for evaluating freeze-induced damage to chicken spermatozoa.

Viability of ram testicular spermatozoa following cryopreservation in rete testis fluid

Ram testicular spermatozoa, collected continuously from the cannulated testis, were frozen in rete testis fluid in straws using the cryoprotective agents egg yolk and glycerol. The effect of cryopreservation on the viability of the spermatozoa was assessed by studying their metabolism, morphology, ultrastructure, and radioiodination patterns. Freeze-thawing significantly depressed the respiration rate and glycolytic activity of testicular spermatozoa. Morphologically, there was little evidence of cryodamage in frozen-thawed testicular spermatozoa. Except for some slightly corrugated acrosomes and a more loosely attached plasma membrane over the sperm head, frozen-thawed testicular spermatozoa were indistinguishable from nonfrozen control spermatozoa. Surface radioiodination of frozen-thawed testicular spermatozoa was highly selective and resulted in a labeling pattern similar to that of the nonfrozen controls. In contrast, the radiolabeling pattern of frozen-thawed electroejaculated spermatozoa was characterized by high background radioactivity and low selectivity. These results confirm previous suggestions that testicular spermatozoa have a greater low-temperature tolerance than do ejaculated spermatozoa and indicate that cryopreservation of immature testicular spermatozoa in rete testis fluid with added egg yolk and glycerol may be a useful approach to extend the availability of these cells.

Lipid deficient extender for bovine spermatozoa: its development and use in measuring freezing-induced lipid loss

To facilitate the measurement of lipid losses from spermatozoa due to freezing, three low-lipid seminal extenders containing lactose, bovine serum albumin, or soybean protein were evaluated as potential cryoprotectants. All extenders were formulated to have an osmotic pressure within the range of 270 to 330 mosmol and a pH of 6.8 to 7.0. Soybean protein (Promine-D) maintained the highest post-thaw motility of spermatozoa with similar survival for spermatozoa frozen in ampules and straws. The extender derived from testing several components consisted of Tris(hydroxymethyl) aminomethane (245 mM), and citric acid monohydrate (78mM), as the buffering compounds; and fructose (69 mM), glycerol (7% vol/vol), and Promine-D (1.5% wt/vol). Post-thaw sperm motility of approximately 40% was not different from the Tris-egg yolk control. Fertility of fresh rabbit semen treated with the extender was normal. After freeze-thawing, protected spermatozoa contained more lipid (1.61 versus 1.20 mug/10-6 sperm) and lost less glutamic oxaloacetic transaminase enzyme (102 versus 108 Karmen units) than when Promine-D was not incorporated. However, even with protection by soybean protein, spermatozoa lipid content decreased from 2.43 to 1.61 mug/10-6 sperm after one freeze-thawing. The lipid status of spermatozoa frozen and thawed in conventional bull seminal extenders containing large amounts of lipids is unknown.