No abstract

The response of epididymal bull spermatozoa to hypotonic media was investigated. Experiments in which spermatocrits were plotted versus the reciprocal of medium osmolality indicate that the swelling of the spermatozoa takes place linearly with a decrease in medium osmolality. The mean volume and area of swollen spermatozoa at critical medium osmolality (44 mosmol) were calculated as 126 \ g=m\ m3 and 145 \g=m\2, respectively. Data available on the isotonic volume, area and water content of the spermatozoa indicate that, at critical medium tonicity, the cells have increased their volume 3\m=.\78to 3\m=.\94times without an apparent increase in area and that, according to conventional osmotic theory, they may be regarded as osmometers with a value of the Ponder's R' correction factor in the range 0\m=.\81to 0\m=.\91, i.e. they seem to deviate from the state of a`p erfect osmometer' by 9 to 19%.

No abstract

After centrifugation of a mobile-sperm suspension, the spermatozoa will begin to move upwards from the sediment into the supernatant. This fact constitutes the background to the following method for comparative estimation of thè amounts of motility' in different test suspensions. The method is simple, adequately objective, and recordings can be made in parallel on several different test suspensions in which the spermatozoa have been in contact with various media for an identical time.Test suspensions containing 0\m=.\5% of cells (see below) were prepared from well-mixed stock suspensions of spermatozoa pooled from the cauda epididymidis of a varying number of gonads from slaughtered bulls. When the effects of different drugs upon sperm kinetic activity were studied, the suspending medium was a Ringer solution in which the 100-ml 0\m=.\9% NaCl (0\m=.\154m) component of Mann's Ringer solution (Mann, 1964) was replaced with a 0\m=.\191 m-NaCl solution. This replacement rendered the Ringer solution approximately isosmotic with the fluids from the cauda epipidymidis, which have a freezingpoint depression of \ m=-\ 0\ m=. \ 66\ s=deg\ C (Salisbury & Cragle 1956). When the effects of different ions were investigated, the ionic composition of the 100-ml component of the Ringer solution was altered. All suspending media also contained 0\m=.\1% glucose.Experiments on spermatoza from different stock suspensions were preceded by a preliminary test, in which a 2-0-ml sample of a control suspension con¬ sisting of 0-15 ml of stock suspension +10-0 ml of medium was centrifuged at room temperature (23 to 24°G ) for 15 min at 2000 g. The medium consisted of a mixture of 0-191 M-NaCl and NaF Ringer solution in the proportion of 15:1, in which the sperm motility was immediately blocked by the fluoride (see Lindahl & Wedin, 1963). With the aid of the spermatocrit values then obtained (which usually fell within the range of 0-008 to 0-012 ml), the quantity of stock suspension was calculated which, after mixing with 100 ml of a given test medium and subsequently centrifuging in a 2-0-ml sample, would-if the spermatozoa were immotile-give a spermatocrit value of 0-010 ml. This procedure ensured that the 'sperm rises' determined for different test suspen¬ sions in different experiments could be related to the same spermatocrit value.In the calibrated spermatocrit tubes used (AB Grave, Stockholm, Sweden), the lengths of the narrow parts, which were graded in volume fractions from zero to 0-080 ml (Text- fig. 1), were almost identical (range 54-5 to 55-5 mm), i.e. a volume fraction of 0-001 ml had a height of approximately 55/80, or 0-69 mm. 427

The water content of epididymal bull spermatozoa in media of osmolalities corresponding to those of seminal plasma and to the fluids from the cauda epididymidis was determined by a gravimetricvolumetric method as 0\m=.\586\ m=+-\ 0\m=.\0052and 0\m=.\512\m=+-\0\m=.\0086ml per ml of cells, respectively. It was related to the ionic concentrations in mmol/ litre of spermatozoa determined by the conversion of the mean values of the major cations expressed as mequiv./litre, mg/100 g, or mg/100 ml, established by previous authors. The osmolalities of the intracellular fluids were also calculated. They were compared with the osmolalities of the extracellular fluids, the comparison making it possible to perform an introductory analysis of the osmotic-equilibrium states of bull spermatozoa.The calculated osmolality of the cytosol of epididymal spermatozoa was found to be about 40 mosmol less than that of the epididymal fluids. This discrepancy from the state of osmotic equilibrium is not serious when considering the errors, which are probably inherent in the values of both the ion and water-content determinations. The osmolality of the cytosol of ejaculated spermatozoa was calculated as 1\m=.\7times greater than that established for seminal plasma. If the calculated value is reasonably correct, this should imply that, for the existence of identical concentrations of osmotically active particles on both sides of the cell membrane of spermatozoa suspended in seminal plasma, a fraction of the intracellular ions, amounting to about 38%, must be assumed to be 'bound'.