Seminal Plasma Osmolality Research Articles

Motility activation of rainbow trout spermatozoa at pH 6.5 is directly related to contamination of milt with urine

Semen samples (collected using a catheter, n=5) were experimentally contaminated with urine (10 – 30%) and incubated for 2 and 4h. The percentage of sperm motility was measured at pH 6.5 and in D532 solution (pH 9.0). Contamination of rainbow trout milt with urine led to dose-dependent decrease in seminal plasma osmolality, from 301±3 to 203±2mOsm/kg, for 0 and 30% contamination, respectively. Contamination with urine significantly reduced the ability of rainbow trout spermatozoa to be activated at pH 6.5 after 2 and 4h of incubation. On the other hand, no changes of motility in pH 9.0 saline were observed at the same time. Our results suggest, that the ability of spermatozoa to activate motility at pH 6.5 can reflect sub-lethal changes of rainbow trout spermatozoa after urine contamination.

Evaluation of Spermiation Indices with Multiple Sperm Collections in Endangered Sterlet (Acipenser ruthenus)

This study investigated the effects of multiple collections of sperm on endangered sterlet (Acipenser ruthenus) sperm functional parameters [spermatozoa motility and curvilinear velocity (VCL)] as well as on protein concentration and osmolality of seminal plasma. The average sperm volume and mean spermatozoa concentration per male were significantly altered with multiple collections. On the other hand, no significant effect of multiple collections on protein concentration of seminal plasma was observed. In all experimental groups, moderate impact of sequential collection on osmolality (p < 0.05) of seminal plasma was observed. Ninety to 100% of motile spermatozoa were observed at 15 s after activation, with an average VCL of 181.12 ± 19.10 μm/s. After 90 s, average VCL decreased to 130 ± 26 μm/s. Motility was maintained for up to 4 min. The maximum percentage of motile spermatozoa was observed after the third collection of sperm. The spermatozoa VCL increased significantly with subsequent collections. The results of this study provide new data on the effects of multiple collections on quantitative and qualitative parameters of sperm in sterlet. The data confirmed that the sequential stripping has no negative effect on the percentage of motility and spermatozoa velocity. This should be beneficial for the development of sterlet aquaculture programs.

Spermatozoa Concentration, Seminal Plasma Composition and Their Physiological Relationship in the Endangered Stellate Sturgeon (Acipenser stellatus) and Russian Sturgeon (Acipenser gueldenstaedtii )

Comparative studies of ionic composition, osmolality, protein concentration and pH of seminal plasma along with spermatozoa concentrations were carried out in stellate sturgeon, Acipenser stellatus, and Russian sturgeon, Acipenser gueldenstaedtii. Analysis of A. gueldenstaedtii sperm showed significantly higher concentrations of Na(+) (34.58 ± 4.61 mm), Ca²(+) (0.35 ± 0.12 mm), Mg²(+) (0.70 ± 0.25 mm), Cl(-) (13.50 ± 4.04 mm) and proteins (0.60 ± 0.29 mg/ml) in the seminal plasma than did seminal plasma of A. stellatus: Na(+) (20.08 ± 10.75 mm), Ca²(+) (0.28 ± 0.06 mm), Mg²(+) (0.29 ± 0.05 mm), Cl(-) (7.50 ± 3.00 mm) and 0.30 ± 0.11 mg/ml proteins. Significantly higher concentration of K(+) (5.42 ± 1.06 mm) was observed in A. stellatus compared to A. gueldenstaedtii K(+) (2.29 ± 0.50 mm). Concentration of Na(+) was positively correlated with osmolality (r = 0.819), levels of Cl(-) (r = 0.922) and Mg²(+) (r = 0.727) and pH (r = 0.848). The concentration of Mg²(+) was positively correlated with protein concentration (r = 0.774), Na(+) (r = 0.727), Cl(-) (r = 0.872) and Ca²(+) (r = 0.801). A positive relationship was also found between concentration of K(+) and spermatozoa concentration (r = 0.709). Results revealed strong inter-species differences in several parameters. The data should be useful for artificial fertilization and for cryopreservation of sturgeon sperm.

Semen characterization and sperm structure of the Amazon tambaqui Colossoma macropomum

Seminal features of tambaqui were evaluated after hormonal induction of spermiation with common carp pituitary extract. Seventeen adult (6.1 ± 0.9 kg, 62 ± 6 cm) males were collected from earthen ponds and transported to indoor concrete tanks. Semen was evaluated according to volume, pH, osmolality, motility, concentration, viability, sperm morphometry and morphological abnormalities. The semen of tambaqui was white and milky. The volume was 10.2 ± 5.1 mL at pH 8.0 ± 0.1, and yielded a concentration of 9.1 × 109 spermatozoa mL−1 while seminal plasma osmolality was 260 ± 7.3 mOsm kg−1. The percentage of viable sperm cells was determined with 97.0 ± 2.0% and 87.0 ± 8.0% using an eosin-nigrosin staining and fluorescent live-dead kit (propidium iodide and SYBR-14), respectively. A negative correlation (−0.65) between semen pH and sperm motility was observed suggesting this feature might influence the tambaqui sperm kinetics. Morphometrically the spermatozoa were on average 35.48 ± 1.55 μm long with a roundish head (mean length: 2.73 ± 0.21 μm; mean width: 2.58 ± 0.18 μm; n = 250 spermatozoa), without an acrosome, and presented a long midpiece (2.90 ± 0.52 μm) and flagellum (29.84 ± 1.63 μm). About 15.8% of the spermatozoa carried morphological abnormalities, with bent tail being the most frequent defect (7.81 ± 3.12%). The characterization of tambaqui semen favors the development of more precise and efficient procedures for its analysis and utilization in controlled breeding.

Physico-biochemical parameters and protein profiles of sperm from beluga Huso huso

Summary Basic physico-biochemical parameters and protein profiles of sperm from beluga (Huso huso), have been evaluated. The results show a stable spermatozoan velocity (ranging from 136.23 ± 5.63 to 105.78 ± 5.27 μms−1) and motility during 2 min post activation, as well as a long duration of the overall spermatozoa motility period (up to 5 min). Mean values were determined for seminal plasma protein concentration (0.29 ± 0.16 mg ml−1), spermatozoa concentration (0.28 ± 0.27 × 109 spz ml−1), seminal plasma osmolality (51.33 ± 4.91 mOsmol kg−1), the pH (8.49 ± 0.01) and Na+ (18.97 ± 3.65 mm), K+ (2.83 ± 1.36 mm), Ca2+ (0.19 ± 0.06 mm), Mg2+ (0.49 ± 0.23 mm) and Cl− (6.33 ± 0.58 mm) concentrations. Moreover, in seminal plasma, five protein bands with molecular weights (MW) of 71, 49, 46, 34, 29 kDa were identified. In spermatozoa, about 100 spots with molecular weights varying from 26.5 to 107 kDa and iso-electric points ranging from 5 to 9.5 were found. The observed physiological and biochemical properties, together with protein patterns, should be considered for the development of methods for controlled reproduction and sperm cryopreservation for the highly endangered beluga sturgeon.

Osmolality of Seminal Plasma as an Indicator of Milt Contamination with Urine Based on the Example of the Tench &lt;i&gt;Tinca tinca&lt;/i&gt; (L.)

Osmolality of Seminal Plasma as an Indicator of Milt Contamination with Urine Based on the Example of the Tench &lt;i&gt;Tinca tinca&lt;/i&gt; (L.)

Sperm motility and seminal plasma characteristics in Barbus sharpeyi (Günther, 1874)

Spermatozoa concentration, ionic composition, osmolality, glucose and total protein contents of seminal plasma and sperm motility were determined in Barbus sharpeyi (Cyprinidae, Teleosotei). Spermatozoa concentration ranged from 9.77 to 20.20 × 109 spermatozoa mL−1. Osmolality (mOsmol kg−1) and ionic contents (mM L−1) of the seminal plasma were 274.5±9.0, 70.0±3.4 Na+, 28.8±0.9 K+, 101.7±3.1 Cl−, 0.9±0.1 Mg2+ and 2.1±0.1 Ca2+ respectively. Total protein and glucose were 5.3±0.2 g L−1 and 76.7±4.3 mM L−1 respectively. Sperm motility was initiated in a hypo-osmotic condition, composed of either an ionic (KCl or NaCl) or a non-ionic (sucrose) activation medium. Duration of sperm motility was very short: <2 min after activation in distilled water. Percentage of motile spermatozoa was significantly higher in an activation medium containing NaCl compared with that of distilled water. An activating medium containing NaCl or KCl higher than 150 mM or sucrose higher than 275 mM totally inhibited the activation of sperm motility. Immediately after sperm activation, wave(s) propagated along the flagellum, but waves were restricted to the proximal part of the flagellum (close to the head) at 1 min post activation. Studied characteristics in the present study were compared with those of other cyprinids for understanding inter-species differences.

Relationships between reproductive characteristics in male Vimba vimba L. and the effects of osmolality on sperm motility

In Vimba vimba, GSI, sperm volume, and spermatozoa concentration range from 3.4–7.4 %, 0.1–1.1 ml, and 13.3–34.8 × 10 9 spz ml −1, respectively. Gonad mass (r = 0.90) and sperm volume (r = 0.35) significantly correlated with weight of males. Significant correlation was also found between gonad mass and length of males (r = 0.85). Sperm motility (r = 0.99) and velocity (r = 098) significantly decreased after activation in Tris-HCl 20 mM, pH 8.5. Osmolality of the seminal plasma was 273.2 mOsmol kg −1. Sperm motility and velocity were significantly affected by the osmolality of the activation medium (P < 0.01). Hyper-osmolality compared to seminal plasma osmolality totally suppressed the sperm activation. At 15 s post-activation, the sperm motility significantly decreased at 240 mOsmol kg −1 in KCl or NaCl media. The highest sperm motility and velocity (at 60 s post-activation) were observed at 200 mOsmol kg −1 in NaCl, KCl, or sucrose media. In all treatments, the tip of the flagellum of spermatozoa became curled into a loop shape after activation of sperm in distilled water containing 20 mM Tris-HCl, pH 8.5 that shortened the flagellum.

Seasonal variations in seminal plasma and sperm characteristics of wild-caught and cultivated Atlantic cod, Gadus morhua

The objective was to investigate changes, throughout the spawning season, in body size attributes and quantitative semen characteristics of wild-caught and cultivated Atlantic cod, Gadus morhua L. Sperm velocity increased significantly throughout the spawning season of cod from both origins. Curvilinear velocity (VCL; 30 sec post-activation) increased from 78.9 ± 6.5 to 128.2 ± 6.5 μm/sec (mean ± SEM) between the beginning and end of the spawning season, respectively, for wild-caught cod, whereas for cultivated fish, it increased from 26.6 ± 2.4 to 48.9 ± 3.1 μm/sec between January and March. Spermatocrit did not undergo a significant seasonal change in wild-caught cod but did thicken for cultivated cod (24.6 ± 4.2% in January to 40.5 ± 4.4% in April; P < 0.01). Sperm head area, perimeter, length, and width declined significantly at the end of the spawning season of cod from both origins (all P values < 0.01). Seminal plasma osmolality and Na + ion concentration followed a dome-shaped function through the spawning season for both wild-caught and cultivated cod (P < 0.05). For cultivated cod, seminal plasma pH was significantly lower at the start of the spawning season (P < 0.001), whereas Ca 2+ increased then decreased (P < 0.05). Body size attributes, spermatocrit, and seminal plasma constituents had significant relationships with sperm activity variables. These relationships varied as a function of time post-activation, month, and fish origin. Our findings may be used to (i) assess spermiation stage without killing males; (ii) optimize semen collection for hatchery production; (iii) characterize the potential impact of farming on sperm quality; and (iv) improve success of sperm cryopreservation and short-term storage.

Sperm quality in male Barbus barbus L. fed different diets during the spawning season

Sperm quality of Barbus barbus L. was compared among the three following dietary regimes: Group A, fed 100% commercial diet (Karpico containing 33% crude protein and 6% fat), Group B, fed 78% commercial diet and 22% frozen chironomid (Chironomus plumosus) larvae, and Group C, fed 56% commercial diet and 44% frozen chironomid larvae. Concentrations of polyunsaturated fatty acids (PUFAs) in Group A, B, and C were 39.1, 42.0, and 44.6, respectively, as a percentage of total fatty acids. Sperm morphology, volume, concentration and motility, total number of spermatozoa, and osmolality of the seminal plasma were compared during the spawning season. Dietary regime did not influence sperm volume, concentration, or total number of spermatozoa, osmolality of seminal plasma, or the percentage of motile sperm, but significantly affected sperm morphology (except for anterior and posterior parts of the midpiece) and sperm velocity (P < 0.05). Groups B and C showed similar sperm characteristics during the spawning season compared to Group A. Almost all parameters changed either among or within groups during the spawning season, suggesting differences in terms of the optimal time for sperm collection. The best time for sperm collection was March for Group A, but April for Groups B and C, when the osmolality of the seminal plasma measured 289 mOsmol kg(-1) and sperm motility was maximal. Spermatogenesis, hydration, and cell decomposition were confirmed as the three major parameters controlling sperm characteristics during the spawning season. The possible correlation between sperm morphology and motility requires further study.

Chilled storage of walking catfish ( Clarias macrocephalus) semen

The aim of the present study was to determine changes in sperm quality of walking catfish ( Clarias macrocephalus) during its spawning season, and develop a simple and efficient protocol for the chilled storage of semen at 4 °C. Semen samples were evaluated monthly during April–November in 2006. Percentage of spermiating males and sperm motility peaked during the middle of the spawning season, June–September. Sperm density and seminal plasma osmolality increased significantly ( P < 0.05) throughout the spawning season, while semen pH did not change during this period. The effects of extender, dilution ratio and timing of chilled storage on successful storage period of extended semen were examined during the years 2006–2007. Fresh semen was diluted 1:1 with several sperm extenders, calcium-free Hanks' balanced salt solution (Ca–F HBSS), Hanks' balanced salt solution (HBSS), extender 7 (NaCl 5.780 g, KCl 2.558 g, CaCl 2·2H 2O 0.103 g, NaHCO 3 0.235 g, MgCl 2·6H 2O 0.220 g, pyruvate 6.0 g, citric acid 0.100 g, HEPES buffer 2.380 g in 1000 mL distilled water), extender 13 (NaCl 8.760 g in 1000 mL distilled water), and modified Cortland, in tissue culture flasks. Longest successful storage period of sperm was 10 days with Ca–F HBSS. Semen diluted with Ca–F HBSS at 1:1, 1:2 or 1:4 ratios significantly lengthened ( P < 0.05) the storage period over those at dilutions of 1:9 or 1:19. To determine the effect of season on the success of chilled storage, semen diluted with Ca–F HBSS at a ratio of 1:4 was prepared at three sampling intervals in the beginning (May), middle (August) and end (November) of spawning season in 2007. Extended semen prepared in August remained motile (20 ± 3.1%) for as long as 10 days, whereas those prepared in May or November were immotile on days 9 and 7 of storage, respectively. Extender-preserved semen was capable of fertilizing eggs as efficiently as fresh semen within two days of storage. A significant decrease in fertilization and hatching rates of extender-preserved semen compared to fresh semen on days 4 and 6 was due to low sperm motility. These results demonstrate that semen of walking catfish can be stored for short term at 4 °C without appreciably affecting motility and fertilization.

Relationship between semen characteristics and body size in Barbus barbus L. (Teleostei: Cyprinidae) and effects of ions and osmolality on sperm motility

The objectives of the present study were to determine the relationships among length and weight of males, sperm volume, spermatozoa concentration, total number of spermatozoa, ionic contents and osmolality of seminal plasma in Barbus barbus. The effect of osmolality on sperm motility parameters after activation in NaCl, KCl, or sucrose solutions was also examined. There were significant correlations between spermatozoa concentration – length ( R = + 0.7) and – weight ( R = + 0.8) of males. No significant correlations were observed between the total number of spermatozoa, sperm volume, and length and weight of males. Seminal plasma osmolality was higher when the total number of spermatozoa ( R = + 0.6) and sperm volume ( R = + 0.6) were higher. Sperm motility and velocity was positively correlated with osmolality ( R = + 0.5). The correlation between sperm motility and K + was negative ( R = 0.5), but positively correlated with Ca 2+ ( R = 0.8), Na + ( R = 0.8), and Cl − ( R = 0.8). There was a rapid decrease ( P < 0.05) in sperm motility parameters after sperm activation. Just after sperm activation, beating waves propagated along the full length of flagella. At latter stages post sperm activation, the waves appeared only in proximal part of the flagellum. The highest spermatozoa velocity and percentage of motility were observed at 215–235 mOsmol kg − 1 in NaCl, KCl or sucrose. The tip of the flagellum became curled into a loop shape which shortened the flagellum after activation of sperm in distilled water. B. barbus sperm is very similar to that of other cyprinids in terms of ionic contents and osmolality of the seminal plasma, mechanism of sperm activation and behavior and motility of sperm during swimming period.

Effects of osmolality on sperm morphology, motility and flagellar wave parameters in Northern pike ( Esox lucius L.)

Northern pike ( Esox lucius L.) spermatozoa are uniflagellated cells differentiated into a head without acrosome, a midpiece and a flagellar tail region flanked by a fin structure. Total, flagellar, head and midpiece lengths of spermatozoa were measured and show mean values of 34.5, 32.0, 1.32, 1.17 μm, respectively, with anterior and posterior widths of the midpiece measuring 0.8 and 0.6 μm, respectively. The osmolality of seminal plasma ranged from 228 to 350 mOsmol kg −1 (average: 283.88 ± 33.05). After triggering of sperm motility in very low osmolality medium (distilled water), blebs appeared along the flagellum. At later periods in the motility phase, the tip of the flagellum became curled into a loop shape which resulted in a shortening of the flagellum and a restriction of wave development to the proximal part (close to head). Spermatozoa velocity and percentage of motile spermatozoa decreased rapidly as a function of time postactivation and depended on the osmolality of activation media ( P < 0.05). In general, the greatest percentage of motile spermatozoa and highest spermatozoa velocity were observed between 125 and 235 mOsmol kg −1. Osmolality above 375 mOsmol kg −1 inhibited the motility of spermatozoa. After triggering of sperm motility in activation media, beating waves propagated along the full length of flagella, while waves appeared dampened during later periods in the motility phase, and were absent at the end of the motility phase. By increasing osmolality, the velocity of spermatozoa reached the highest value while wave length, amplitude, number of waves and curvatures also were at their highest values. This study showed that sperm morphology can be used for fish classification. Sperm morphology, in particular, the flagellar part showed several changes during activation in distilled water. Sperm motility of pike is inhibited due to high osmolality in the seminal plasma. Osmolality of activation medium affects the percentage of motile sperm and spermatozoa velocity due to changes in flagellar wave parameters.

산천어(Oncorhynchus masou masou) 정자의 냉동보존에 미치는 희석액과 동해방지제의 영향

We experimentally determined the physico-chemical properties of seminal plasma as well as the sperm cryopreservation techniques of masou salmon, Oncorhynchus masou masou. Seminal plasma contained <TEX>$18{\pm}1mmol/L$</TEX> potassium, <TEX>$144{\pm}4mmol/L$</TEX> sodium, <TEX>$116{\pm}3mmol/L$</TEX> chloride, <TEX>$83.2{\pm}3.1mg/L$</TEX> calcium, <TEX>$14.8{\pm}0.7mg/L$</TEX> magnesium, <TEX>$45{\pm}9mg/L$</TEX> glucose, and <TEX>$1.0{\pm}0.0g/L$</TEX> total protein. The osmolality and pH of seminal plasma were <TEX>$287{\pm}7\;and\;7.7{\pm}0.1mmol/kg$</TEX>, respectively, and the spermatocrit was <TEX>$28{\pm}2$</TEX>. The rate of embryonic survival at the eyed-stage and the hatching rate were highest in 10% methanol with 300 mM glucose. Compared to DMSO or glycerol, methanol served as a better cryoprotectant of masou salmon sperm.

Semen of Perca fluviatilis L.: Sperm volume and density, seminal plasma indices and effects of dilution ratio, ions and osmolality on sperm motility

The objectives of the present study were to characterize sperm volume and density, seminal plasma indices (ionic contents and osmolality) and to study the effects of dilution ratio, ions and osmolality on sperm motility parameters (percentage of motile sperm and sperm velocity) in farmed European perch ( Perca fluviatilis L.). The means of sperm volume (ml), sperm density (×10 9 sperm ml −1) and total number of sperm (volume × density) per fish were 2.75 ± 0.51, 29.19 ± 3.15 and 82.19 ± 15.26. The seminal plasma osmolality (mOsm kg −1), sodium, chloride, potassium and calcium ions concentrations (mM) were measured to be 298.07 ± 5.09, 130.97 ± 2.19, 106.75 ± 2.37, 10.70 ± 0.61 and 2.41 ± 0.09, respectively. At 15 s post-activation of stripped sperm, the percentage of motile sperm (%) and sperm velocity (μm s −1) were 91.90 ± 1.27 and 115.54 ± 1.25, respectively, and decreased significantly following sperm activation ( P < 0.05). The optimal sperm motility was observed when the sperm was prediluted in immobilizing solution (IS) at a ratio 1:50. Prediluted sperm showed the maximum velocity when activated in 2.5 mM Ca 2+, 50 mM K + and sucrose with osmolality 100 mOsm kg −1. Neither Ca 2+ nor K + showed a significant effect on the percentage of motile sperm at 15 s post-activation. Osmolality higher than 200 mOsm kg −1 significantly decreased the percentage of motile sperm, while osmolality of 300 mOsm kg −1 or above totally suppressed sperm motility.

Sperm motility in fishes. (II) Effects of ions and osmolality: A review

The spermatozoa of most fish species are immotile in the testis and seminal plasma. Therefore, motility is induced after the spermatozoa are released into the aqueous environment during natural reproduction or into the diluent during artificial reproduction. There are clear relationships between seminal plasma composition and osmolality and the duration of fish sperm motility. Various parameters such as ion concentrations (K+, Na+, and Ca2+), osmotic pressure, pH, temperature and dilution rate affect motility. In the present paper, we review the roles of these ions on sperm motility in Salmonidae, Cyprinidae, Acipenseridae and marine fishes, and their relationship with seminal plasma composition. Results in the literature show that: 1. K+ is a key ion controlling sperm motility in Salmonidae and Acipenseridae in combination with osmotic pressure; this control is more simple in other fish species: sperm motility is prevented when the osmotic pressure is high (Cyprinidae) or low (marine fishes) compared to that of the seminal fluid. 2. Cations (mostly divalent, such as Ca2+) are antagonistic with the inhibitory effect of K+ on sperm motility. 3. In many species, Ca2+ influx and K+ or Na+ efflux through specific ionic channels change the membrane potential and eventually lead to an increase in cAMP concentration in the cell, which constitutes the initiation signal for sperm motility in Salmonidae. 4. Media that are hyper- and hypo-osmotic relative to seminal fluid trigger sperm motility in marine and freshwater fishes, respectively. 5. The motility of fish spermatozoa is controlled through their sensitivity to osmolality and ion concentrations. This phenomenon is related to ionic channel activities in the membrane and governs the motility mechanisms of axonemes.

Motility Parameters of Rainbow Trout (Oncorhynchus mykiss) Spermatozoa in Relation to Sequential Collection of Milt, Time of Post-mortem Storage and Anesthesia

The present study investigated the effects of sequential collection of milt, time of post-mortem storage and anesthesia on rainbow trout (Oncorhynchus mykiss) sperm motility parameters (using computer-assisted sperm analysis – CASA) as well as seminal plasma osmolality and sperm concentration. The post-mortem storage and time of anesthesia altered motility characteristics of rainbow trout sperm to different extents. The moderate impact of time of anesthesia was manifested in a shortened duration of sperm motility after 10 min exposure of fish to anesthetic. The prolonged post-mortem storage (≥40–60 min), in addition to lowering sperm motility duration, also significantly influenced sperm motility parameters, such as sperm velocities, percentage of motile sperm and sperm trajectory parameters. These results clearly demonstrate that when milt from sacrificed fish is used for sperm motility studies, the time of post-mortem storage significantly alters sperm motility characteristics. Since sperm motility rate and swimming velocity could predict fertilizing ability, detrimental effects of prolonged post-mortem storage may lead to reduced fertilization success. Sperm concentration and seminal plasma osmolality were lower in the first fractions and increased with successive collections of milt. It suggests the presence of urine contamination of the first milt fractions which were collected by stripping. Therefore, testing of sperm concentration and/or seminal plasma osmolality should be mandatory while handling stored milt.

Effects of slow release gonadotropin releasing hormone analog on milt characteristics and plasma levels of gonadal steroids in greenback flounder, Rhombosolea tapirina

Spermiated male greenback flounder ( Rhombosolea tapirina) were implanted with gonadotropin releasing hormone analog (GnRHa) pellets at different dosages to examine their effects on milt characteristics and plasma levels of testosterone (T), 11-ketotestosterone (11KT) and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP). Milt and blood samples were collected for up to 28 or 42 days post-implantation (p.i.) in two separate experiments using fish that were slightly or moderately spermiated, respectively. In both experiments, fish treated with GnRHa pellets showed a consistent and significant increase in milt volume relative to controls, and the increase of milt volume was more rapid than the increase in numbers of spermatozoa. Spermatocrit (Sct) was significantly lower in GnRHa-treated fish than in controls. Plasma levels of T and 11KT were elevated at 7 and 14 days p.i. in slightly spermiated fish treated with GnRHa and elevated plasma T and 11KT levels were accompanied by increased milt volume early in the spermiation period. In contrast, there was no significant difference in plasma T levels between GnRHa-treated and control fish in fish that were moderately spermiated at the time of implant. Treatment with GnRHa tended to result in lower plasma levels of 11KT and higher levels of 17,20βP relative to controls, and there was a positive relationship between the elevation of plasma 17,20βP and the increase in milt volume in response to implantation of GnRHa pellet. Slow release GnRHa administration had no effect on sperm activity or pH and osmolality of seminal plasma in either experiment.

Chemical composition and osmolality of seminal fluid of Acipenser persicus; their physiological relationship with sperm motility

Determination of semen quality is necessary to understand the basic biochemical processes occurring during motility of sperm and during fertilization to evaluate the reproductive ability of different fish species and to create an optimal environment for storage of spermatozoa; in this regard less information is available for Acipenseridae compared with Cyprinidae and Salmonidae. The aim of the present study is to determine chemical composition and osmolality of seminal fluid and their relationship with sperm motility in Acipenser persicus. The results obtained show that sodium (Na+), chloride (Cl−) and potassium (K+) were predominant ions in the seminal plasma and the average of osmolality of seminal plasma was 82.56 mOsm kg−1. The higher chemical contents and osmolality compared with other sturgeon species reveal species-specific characteristics and high secretory activity of spermatic duct in A. persicus. Significant positive correlations were observed between osmolality-Cl−, Na+-osmolality and Na+–Cl− (P<0.05, P<0.001 and P<0.05 respectively). But statistically significant correlation was not observed between seminal plasma parameters and sperm motility. Probably, the Na+ and Cl− are the main electrolytes playing a major role in maintaining the osmolality of the seminal plasma and the viability of the spermatozoa in vivo.

Sperm-cell volumetric measurements as parameters in bull semen function evaluation: correlation with nonreturn rate.

Sperm-cell volume, measured electronically by cell counter, is a parameter providing information about the state and integrity of the plasma membrane by determining cell osmotic reactivity (swelling level). Electronic volume measurement is a modification of the hypo-osmotic swelling test, based on the increase in sperm volume in response to hypo-osmotic stress. In this study the volumetric method was applied to bull ejaculates, and the relationships of volumetric parameters, osmolality of seminal plasma, and concentration of sodium and potassium ions in seminal plasma, with the nonreturn rate (NRR) were examined. Significant correlations were found between volumetric parameters, conventional spermatological parameters, and NRR. The relative volume shift of the mean volume correlated significantly with motility before and after thawing (P < 0.05). NRR correlated significantly with iso-osmotic cell volume (- 0.49; P < 0.05) and with the relative volume shift (0.51, P < 0.05). The prediction level of regression models was improved when volumetric parameters (iso-osmotic cell volume) were included in the multiple regression model. Therefore, using electronic volume measurement as a component for fast, correct and valid (up to 50,000 cells), recording sperm-cell population may help to evaluate ejaculate quality more precisely.