Sperm In Preparation Research Articles

Lipocalin 2 as a membrane-reorganizing agent.

Lipocalins are a class of proteins that scavenge hydrophobic molecules in diverse contexts, including the immune system, the nervous system, and cancer. A recent study by Watanbe et al. identifies lipocalin 2 produced by the female mouse reproductive tract as a sperm-capacitating agent that alters the membrane properties of sperm in preparation for fertilization. The potential for lipocalins to act as general modulators of plasma membrane bioactivity is discussed.

The use of iodixanol as a density gradient material for separating human sperm from semen.

Iodixanol, a new nonionic density gradient material with relatively low osmolality and high density, was evaluated to determine its suitability for the separation of human sperm from semen for their subsequent therapeutic use. Using a three-layer iodixanol gradient (approximately 1.17/1.15/1.05 g/mL), sperm were centrifuged at 1000g for 30 min and collected from the 1.05/1.15 interface. Using this method, a mean of 78% of the motile and 99% of the morphologically normal sperm originally present in the semen were recovered at the interface. There was no significant increase in the percentage of motile or morphologically normal sperm in the final preparation compared to the original semen. Sperm survived iodixanol density gradient centrifugation well, showing only modest declines in motility (18%) and velocity (35%) during a subsequent 24-h incubation period. When iodixanol was compared to Percoll density gradient centrifugation with semen from the same ejaculate, there was no significant difference between methods with regard to sperm yield, enrichment of motile or morphologically normal sperm in the preparation or sperm survival following separation. Iodixanol provides a suitable, nontoxic alternative to Percoll for the preparation of human sperm for therapeutic use.

Sexual differences in over-winter torpor patterns of Richardson's ground squirrels in natural hibernacula.

Over-winter torpor patterns of Richardson's ground squirrels hibernating in southern Alberta were monitored with temperature-sensitive radiocollars to determine if these patterns differed between males and females in a manner related to the greater costs of mating effort by males than females. The hibernation season (from immergence to emergence) was composed of three periods: post-immergence euthermy, heterothermy, and pre-emergence euthermy. The hibernation season was shorter for juveniles than adults both among males (< 150 versus 234 days) and females (185 versus 231 days), a reflection of the later immergence into hibernation by juveniles. However, regardless of the absolute duration of hibernation, heterothermy accounted for a smaller proportion of the hibernation season of males (93±5%) than females (98±1%) and, within the heterothermal period, males had shorter torpor bouts and longer inter-torpor arousals. Overall, males spent a smaller proportion of the hibernation season in torpor (85±6%) than females (92±1%). This sexual difference was largely attributable to the longer duration of preemergence euthermy for males than females. Males terminated torpor in January and February, when hibernacula were at their coldest, then remained euthermic for 8.8 days (range 0.5-25.0 days) before emergence. In contrast, females terminated torpor in March, when hibernaculum temperatures were increasing, then remained euthermic for only 1.1 days (range 0.5-2.0 days) before emergence. Males lost less mass per euthermic day during hibernation than females (7.0 versus 9.3 g/day). Males and females hibernated at similar depths (56 cm), but males had larger chambers than females (18 versus 16 cm3/g). Many males, but no females, cached seeds in the hibernaculum. Males met the costs of thermogenesis and euthermy from a combination of fat reserves and food caches, whereas females relied solely on fat. Access to food caches permitted males to terminate torpor several weeks in advance of emergence, during which time they recouped mass and developed sperm in preparation for the forthcoming mating season.

Epididymal functions and their hormonal regulation.

The epididymis is a complex organ which maintains a specific intraluminal environment thought to be important for effecting sperm maturation in proximal regions and sperm storage in distal regions of the duct. The composition of the internal milieu is achieved both by transport between blood and lumen (and vice versa) and by synthesis and secretion into the lumen. Several low-molecular weight organic molecules achieve high concentration in the epididymal lumen, but their functions in the events of sperm maturation and storage still remain unclear. Metabolic processes occurring within epididymal tissue and the absorptive and secretory activity of the epididymal epithelium are regulated by androgens. The synthesis of some, but not all, secretory proteins is also androgen-dependent. In addition to androgens, other hormones and local testicular factors may influence epididymal function. There is now increasing evidence that epididymal-specific and androgen-dependent secretory proteins play a fundamental role in modifying the surface characteristics of sperm in preparation for the events of fertilization.

Effect of the Technique of Staining on Sperm Morphology

The effect of four different techniques of staining semen smears on the proportion of various types of abnormal sperm were studied. These techniques were—the conventional method, the direct mixing method, the dipping and blotting method and the ignition technique. The results of the present study indicate that as long as semen smears are made with the utmost care, using proper materials and techniques, the proportion of abnormal sperm in preparations obtained by different staining procedures remains relatively constant. Even when semen smears were subjected to such a drastic method as the ignition technique of staining, the sperm structure remained unaffected. The direct mixing method, the dipping and blotting method and the ignition technique are all very simple and rapid methods of staining and are very well adopted for practical application in routine artificial insemination work. From the present study, it is concluded that the most important step in the morphological evaluation of semen samples is the process of preparing the semen smears.