Estimation of number, mean size and size distribution of human spermatozoa in oligospermia using a Coulter counter

On-chip determination of spermatozoa concentration using electrical impedance measurements

In this article we describe the development of a microfluidic chip to determine the concentration of spermatozoa in semen, which is a main quality parameter for the fertility of a man. A microfluidic glass-glass chip is used, consisting of a microchannel with a planar electrode pair that allows the detection of spermatozoa passing the electrodes using electrical impedance measurements. Cells other than spermatozoa in semen also cause a change in impedance when passing the electrodes, interfering with the spermatozoa count. We demonstrate that the change in electrical impedance is related to the size of cells passing the electrodes, allowing to distinguish between spermatozoa and HL-60 cells suspended in washing medium. In the same way we are able to distinguish between polystyrene beads and spermatozoa. Thus, by adding a known concentration of polystyrene beads to a boar semen sample, the spermatozoa concentrations of seven mixtures are measured and show a good correlation with the actual concentration (R(2)-value = 0.97). To our knowledge this is the first time that the concentration of spermatozoa has been determined on chip using electrical impedance measurements without a need to know the actual flow speed. The proposed method to determine the concentration can be easily applied to other cells. The described on-chip determination of the spermatozoa concentration is a first step towards a microfluidic system for a complete quality analysis of semen.

The counting and sizing of spermatozoa from ten animal species using a Coulter counter

Accurately calibrated Coulter Counters, Models ZB Industrial and F, were used to count and size spermatozoa before and after Zaponin treatment which lyses accompanying debris, droplets and peripheral sperm cytoplasm. Sperm specimens from the cauda epididymis of the rabbit, Guinea pig, hamster, rat and mouse were without accompanying particles and could be sized without Zaponin treatment. The large acrosome cap of the guinea pig swelled rapidly when the spermatozoa were released into an isotonic solution and measurement was only possible after equilibrium had been reached. Zaponin treatment completely dissolved rat and hamster spermatozoa within a few seconds and about 50% of the mouse spermatozoa. Spermatozoa form the cauda epididymis of the bull were accompanied by some unspecific debris which made size determination without Zaponin treatment difficult. A separate population of cytoplasmic droplets was not present and the amount of accompanying cytoplasm, as shown by its removal with Zaponin, was the least for the species examined. The size of spermatozoa in ejaculated specimens from the dog varied considerably according to whether the cytoplasmis droplet was still present, but after Zaponin treatment all specimens were about the same size. Ejaculated specimens from the European wild boar contained a separate population of small droplets which were sufficiently different in size from the spermatozoa to allow separate counting and sizing without Zaponin treatment. Ejaculated specimens from the Rhesus monkey required incubation to release the spermatozoa from the clot before they could be counted and sized. Their size tended to vary slightly according to the length of incubation. Ejaculated specimens from the rabbit and from man were so heavily contaminated with debris that counting and sizing was not possible without Zaponin treatment. The relationship between the amount of debris and the numbers of spermatozoa was extremely variable. The debris in human specimens was separated from the spermatozoa by downward fractionation of the motile spermatozoa into increasing concentrations of bovine serum albumin, so allowing measurement of untreated spermatozoa for the first time. The sperm size distribution curves for all the ten species examined, both before and after Zaponin treatment, were positively skewed. The peaks were broader and flatter when Zaponin was not used. Sperm sizes, in terms of total volume and of the diameter of a sphere of that volume, are given for all the species at both the mode and the mean of the size distribution curves. After Zaponin treatment the mean size was between a volume of 15 and 50 mum3 or an equivalent spherical diameter of 3-5 mum. Before Zaponin treatment all the sperm types were greater than 20% larger by volume and the mean volume was between 25 and 190 mum3.

A new multiparameter flow cytometric method for human semen analysis

BACKGROUND

The objectives of this study were (i) to evaluate whether the combined use of Syto 16 and 7-amino-actinomycin-D (7-AAD) allows the detection of sperm apoptosis and (ii) to describe a new multiparameter flow cytometric method to assess simultaneously sperm concentration (SC), viability and apoptosis as well as leukocyte concentration.

METHODS

Semen samples from 68 patients were evaluated according to World Health Organization (WHO) criteria (normal, n=26; abnormal, n=42). The detection of activated caspases before and after betulinic acid (BA) incubation was carried out in 13 semen samples by flow cytometry using fluorescein-labelled inhibitors of caspases (FLICA). A multiparameter flow cytometric analysis was performed in 55 semen samples. Fluorescent microspheres were used to assess SC. Sperm apoptosis was detected by staining sperm with Syto 16 and 7-AAD. Leukocytes were counted using monoclonal anti-CD45.

RESULTS

A significant correlation between the percentage of the spermatozoa with low Syto 16 fluorescence and the percentage of spermatozoa containing activated caspases was found (r=0.68, P=0.0106; n=13). After incubation with BA, an increase of the percentage of apoptotic cells was observed in all samples, using both the Syto 16/7-AAD and the caspase activation methods. There was a good correlation between flow cytometry and optical microscopy for sperm (r=0.98, P < 0.0001) and leukocyte counting (r=0.64, P <0.0001). The percentage of apoptotic sperm was inversely correlated with both SC (r=-0.303, P=0.0246) and morphology (r=-0.384, P=0.0050) but not with motility.

CONCLUSIONS

The combination of Syto 16/7-AAD provides a sensitive assay to detect sperm apoptosis. The multiparameter flow cytometric method described offers the possibility of a simultaneous, simple, rapid and accurate assessment of several semen parameters.

Measuring mouse sperm parameters using a particle counter and sperm quality analyzer: A simple and inexpensive method

This study examined a method for analyzing the count, motility, and morphology of mouse epididymal sperm, optimizing the diluent, incubation time, sample concentration, and temperature, using a particle counter (CDA-500) to count and size sperm and a sperm quality analyzer (SQA-IIC) to measure sperm motility, quantified as the sperm motility index (SMI). The optimal conditions consisted of a 30-min incubation in D-MEM (Dulbecco's modified Eagle's medium; considering cost and availability) at 37 degrees C, with 5 x 10(6)cells mL(-1) in the original solution. Furthermore, the influence of formalin fixation, and the correlation between the automated counter and a manual method were investigated. The sample fixation had no marked effect on the sperm count or morphology assessment. A linear correlation was observed between the manual and automated methods (y=0.920x +0.276; r(2)=0.571; p<0.001; range: (3-6) x 10(6)). The suitability of the proposed method was confirmed using spermatozoa prepared from mice treated with the reproductive toxin diethylstilbestrol (DES). Using sperm from the cauda epididymidis on one side per mouse, we confirmed that measurement of these sperm parameters using the two devices was simple, rapid, inexpensive, and reproducible.

Review: in vitro spermicidal tests

This review analyzes in vitro spermicidal tests that have been used to evaluate the spermicidal activity of contraceptive products. Special requirements and processes in numerous technologies were also reviewed. Nonoxynol-9 (N-9) was used as an example of a vaginally delivered spermicidal agent, and its spermicidal potency was compared by various spermicidal tests, such as Sander-Cramer, computer-assisted semen analysis, hypoosmotic swelling test, cervical mucus penetration test, and flow cytometry, and advantages and disadvantages of each test were specified. This provides an insight into the different aspects of sperm functionality on which each spermicidal agent exerts its activity. A rationale of the best combination of in vitro spermicidal tests, with particular emphasis on a simple and efficient strategy that targets the complete fertility control, was explained.

The influence of chamber characteristics on the reliability of sperm concentration and movement measurements obtained by manual and videomicrographic analysis

To assess the influence of chamber design and depth on the accuracy and precision of sperm measurements, manual counting of a standardized latex bead solution and automated sperm motility measurements were made using a Makler chamber (Sefi Medical Industries, Haifa, Israel), Neubauer hemocytometer (American Optical Company, Buffalo, NY), and a new, disposable device (Micro-Cell; Cyto Fluidics, Inc., Silver Spring, MD). Bead counts obtained with the Micro-Cell chamber or hemocytometer were not statistically different from those determined by electronic particle counting, whereas Makler chamber counts were 62% higher. Makler counts had a significantly higher standard deviation, suggesting that counts made with this device are less reproducible. Analyzing live sperm samples, the percentage of motile sperm determined using Micro-Cell and Makler chambers were similar. However, significant differences in sperm concentration and mean velocity were found. The Micro-Cell disposable chamber provided consistent and accurate data on sperm concentration, percent motility, and mean velocity. These differences in sperm measurements emphasize the importance of sampling chamber characteristics on data reliability.

Determination of human sperm count and sperm motility using a laser beam and the Doppler effect (LAZYMOT machine)

For 25 consecutive human semen samples, a comparison was made of sperm count and sperm motility values obtained by routine manual methods and by using a machine that measures these functions by analysing the deflection of an impinging laser beam (Lazymot machine). Sperm counts in undiluted semen were approximately 5 times higher with the laser machine. As sperm counts increased to about 300 million/ml the counts obtained by the two methods converged as the chance of the beam hitting a spermatozoon and not another type of particle increased. In semen diluted 1 + 4 with Baker's solution, the uncorrected laser count agreed well with the sperm count obtained using a haemocytometer. Multiplication of the laser count by 5 did not reach the same count as that measured in the undiluted sample, showing that the dilution had dissolved some of the smaller particles. It was recommended to measure laser percentage motility in undiluted semen but the values obtained bore no relationship to those obtained using a haemocytometer and neither did the values obtained for laser percentage sperm with progressive motility. The mean laser velocity of the total motility was 23-64 micron/sec and for the progressive particles was 48-84 micron/sec, values which were much faster that the acceptably normal values of 8-30 micron/sec found for selected progressively motile spermatozoa timed with a stopwatch. The laser machine detected an increase in counts and the presence of residual motility after cytoplasm had been stripped away from the spermatozoa with a saponin reagent. The laser machine was unable to detect any increase in speed on increasing the temperature to 37 degrees C. It was concluded that the Lazymot machine as presently designed is not useful in the andrological laboratory for routine counting and motility determinations, mainly due to the absence of a size discriminator against the multitude of small particles that are present in human semen.

Volumetric analysis of human spermatozoa

In 29 semen samples of men participating in an in vitro fertilization (IVF)-program the spermatozoan volume was determined on an electronic particle analyzer and a routine semen analysis was performed including the estimation of semen volume, sperm concentration, motility and morphology. Twenty three of the 29 semen samples were able to fertilize human oocytes in the IVF-procedure. There was no statistically significant difference noted between the spermatozoan volume of the fertile (16.25 +/- 0.43 cu microns) and the infertile samples (16.9 +/- 0.57 cu microns). Logistic regression analysis indicated that spermatozoan volume was not a significant predictor of fertility. Furthermore, none of the standard sperm parameters appear to be closely related to the mean spermatozoan volume.

Morphometry of spermatozoa using semiautomatic image analysis

Human sperm heads were detected and tracked using semiautomatic image analysis. Measurements of size and shape on two specimens from each of 26 men showed that the major component of variability both within and between subjects was the number of small elongated sperm heads. Variability of the computed features between subjects was greater than that between samples from the same subject.

Effects of exercise conditioning on semen characteristics from hyper- and hypotensive lines of turkeys

Twenty-one male Broad Breasted White turkeys which had been selected for high or low blood pressure were put on an exercise regimen to determine its effect on semen quality. Eleven were from the hypertensive line and 10 from the hypotensive line. Eleven (6 hypertensive and 5 hypotensive) turkeys were placed on an exercise regime of walking (herding) about 1 mile daily for 6 weeks before the experiment began, and then for a further 6 weeks during semen collection. Semen was collected from 11 turkeys on the exercise regime and 10 nonexercised control birds which were kept in their experimental pens during the trial. Both hypertensive and exercised groups showed an improved semen colour score at the first collection period (P less than or equal to 0.09). Only the exercised group showed a significantly (P less than or equal to 0.05) better score than the control group during periods 2 and 3. The hypertensive line showed significantly higher spermatozoa count than the hypotensive line during the first collection period. There was no effect of either exercise or selection for high or low blood pressure on semen volume.

Flow cytometry and sizing for routine andrological analysis

Flow fluorometry and Coulter type sizing analysis of sperm have been applied separately in order to improve human semen analysis. Different methods of sample preparation were evaluated and a protocol involving prestaining pepsin treatment of sperm samples is proposed for fluorometric analysis. The data obtained with fluorometry and sizing analysis result in different kinds of information: Coulter counting allows to automate sperm counting and fluorometry yields more detailed information about normozoospermia and oligozoospermia by determining the proportion of mature spermatozoa and immature germ-cells. These two methods, together with light microscopy, may help to explore the correlation of fertility and pathology of spermatozoa. The aim of these investigations is to yield the preconditions for simultaneous two-parameter analysis of DNA content and cellular size distributions.

Computer-aided counting with the Coulter Counter of low numbers of spermatozoa in human semen

The concentration of spermatozoa in human semen has been assessed by counting in the microscope with a hemocytometer and by counting with the Coulter Counter ZF. The Coulter Counter was supplied with a 100-channel pulseheight analyzer, Channelyzer C-1000, and a tape-punch for further handling of data in a desk-computer. It was found that the number of spermatozoa (less than 10(6) per ml) was over-estimated with the Coulter Counter. By subtraction of the non-spermatozoan background with the aid of mathematical curve-fitting procedures, these values could be corrected. To allow such an adequate analysis without the use of pulse-height analyzer and computer, the background corrections were simulated for the relative number of counts obtained at specified setting of the threshold levels (T) and other variables on the Coulter Counter ZF.

Secular trend in reported sperm counts

Claims that there has been a recent secular decline in splerm counts have been disputed. Protaglonists on both sides of the discussion have based their arguments on data from a few large samples at different times and (mostly) in different places. It is not disputed that the differences between the mean counts in the various samples are statistically significant: what is a tissue is whether a secular decline is responsible. The present not adops a different approach to the problem: an attempt has been made to locate representative data on mean sperm counts of unselected men over the last 45 years. Twenty-nine such means are cited here. There can be no reasonable doubt that these reported mean sperm counts show a decline with time of publication, at least since 1960. It is not easy to see what artifact - other than a real secular trend - might responsible. Accordingly it is concluded that - at least in some places - it seems likely that a secular decline has occurred.

Volume and shape of normal human spermatozoa

An improved apparatus for measuring the electrical size of particles, developed in this laboratory and based on the principle of the Coulter counter, is used to size human spermatozoa. The typical size distribution is unimodel, with a skew to the right. The actual quantity determined by the measuring system is electrical size (i.e., shape factor X volume); in order to extract the volume, it is necessary to obtain an independence measure of particle shape. This is done by estimating the relative contributions of each part of the spermatozoon, and gives a weighted value for the shape factor of 1.28. The mean value of spermatozoa from 25 normal human seminal fluid specimens is found to be 17.4+/-1.46 cu micronm and the modal volume, 15.2+/-1.27 cu micronm. These values are compared with data reported in the literature after correcting the latter for the effects of particle shape. Zaponin does not affect the cell volume distributions, even when used in high concentrations, provided measurements are carried out within the hour.

The splitting of sperm heads from tails in eight mammalian species and the measurement of their sizes

Ejaculated spermatozoa from man, the Euopean wild boar and the bull, and spermatozoa from the cauda epididymes of the rabbit, rat, mouse, hamster and Guinea pig were treated with a sonic bath, a sonic probe, trypsin with and without prior treatment with a sulphhydryl reagent, pronase and alkalis. The fragments produced were counted and sized in an accurately calibrated Coulter Counter, Model ZB Industrial, before and after Zaponin treatment to lyse accompanying debris and the peripheral cytoplasm. Head and tail fractions were separated on sucrose gradients. Each species required different conditions for cleavage or fragmentation. Rabbit and bull spermatozoa were cleaved by the ultrasonic bath exactly into heads and tails, producing twice the number of particles with two peaks in the size distribution curves butith some 60% loss of total sperm volume which became the soluble fraction. The ultrasonic probe, and for the bull, pronase, produced the same cleavage but these more drastic treatments dissolved a considerable portion of the tail fraction. Rodent spermatozoa, especially the rat, were cleaved perfectly into heads and tails by mild trypsin treatment. All the nonrodent spermatozoa were resistent to trypsin cleavage, although prior treatment with a sulphhydryl reagent caused swelling and subsequent trypsin action caused digestion into miscellaneous pieces. Spermatozoa from the boar and from man could not be cleaved by any of the procedures. The sonic probe produced fragmentation with progressive dissolution of the tail fragments and a single peak in the size distribution curve corresponding to small stripped heads. The soluble fraction always constituted a large proportion of the original whole spermatozoa.

Comparison of the particle size distribution curves determined manually and automatically in an accurately calibrated Coulter Counter

An accurately calibrated Coulter Counter, Model ZB Industrial, was used to compare the size distribution curves of seven different standard particles obtained by calculation and after the attachment of a Channelyser, Model C-1000 coupled to an XY recorder. Comparisons were made at the modes of the curves and it was found that the automatic method consistently reported the particles to be slightly larger.

The interconversion of machine settings and size determinations between seven models of Coulter counter as illustrated by values for human spermatozoa

Calibration of the Coulter counter Models ZB Industrial, B Industrial D and D Industrial using 21 standard particles is reported using the same method as previously described for the Models B Medical, F and A. All the machines showed significant differences in design and sensitivity. The additional data allowed the relationship between the machine constant and the aperture diameter to be calculated and volume factors were calculated for each combination of settings on each machine. The general method of interconverting size data and machine settings between the instruments was demonstrated using human spermatozoa as an example.