The functional competence of the human sperm membrane is assessed by studying the swelling reaction of sperm when suspended in a medium of distilled water (water test). Eighty-seven patients with idiopathic infertility were investigated by the water test and the results were compared with various semen parameters. High correlations with the percentage of b-g type swollen sperm in the water test were observed for sperm concentration ( r -.53, p < .05) and percent motility (r = .62, p < .01).The sperm swelling values obtained by the water test correlated well with those obtained by the hypoosmotic swelling test (HOST). Correlation coefficients in b-g and g swelling pattern were 0.89 and 0.71, respectively. The percentage of g-type swelling obtained by the water test was significantly larger than that obtained by the HOST (p < .05), although the two hypoosmotic procedures gave similar percentages of b-g swelling pattern. The percentage of g swelling pattern obtained by the water test correlated well with percent motility ( r = .70, p < ,001). These findings suggest that the water test is more useful for assessing the integrity of the sperm membrane than the HOST. The relationship between this test and subsequent fertility, as well as to other sperm function tests, needs further investigation.

Epidermal growth factor (EGF), first identified in extracts from submaxillary salivary glands of adult male mice, acts as a potent mitogen in a wide variety of cells and tissues in culture. Human EGF, a polypeptide of 53 amino acids isolated from human urine, has been identified in several biological fluids, including prostatic fluid and seminal plasma. Epidermal growth factor content in seminal plasma was measured by RIA. The EGF content in seminal fluid did not change after bilateral vasectomy and the first fraction of sample obtained by split ejaculation contained a significantly larger amount of EGF than the second fraction. Seminal EGF originates from the prostate. There was a close correlation between EGF and zinc contents in seminal fluid. The seminal fluid EGF content was lowered in patients with prostatitis and systemic androgen deficiency. The EGF content in seminal fluid seems to be a reliable indicator of prostatic function.

The ability of pentoxifylline to stimulate sperm motility characteristics was assessed. The effect of pentoxifylline was immediate and lasted for 240 min. The percent motility was increased 1.5-fold when compared with the control at 120, 180, and 240 min after pentoxifylline treatment. Significant increases in velocity and amplitude of lateral head displacement by the agent were observed at 120 min after the start of incubation. Conversely, linearity was reduced by pentoxifylline. Beat-cross frequency did not show any significant change by the agent at any time point. Sperm swelling was not influenced by pentoxifylline throughout the experiment. It would appear that pentoxifylline stimulates sperm motion in vibo with no change ofthe sperm membrane.

By means of a triple-stain technique, the acrosome reaction in infertile and fertile males was investigated. The highest correlations with the percentage of acrosome-reacted sperm were found for motile sperm concentration (r = .60, p < .01) and percent motility (r = .58, p < .05). Significant correlations were also demonstrated between acrosome reactivity and both sperm concentration (r = .50, p < .05) and velocity (r = .40, p < .05). There was only a weak correlation between the percentage of acrosome-reacted sperm and that of swollen sperm. The ratio of acrosome-reacted sperm demonstrated in oligoasthenozoospermic patients was significantly lower than that observed in normozoospermic or fertile males (both, p < .05). There was no significant difference in the ratio of acrosome-reacted sperm between normozoospermic and fertile males. However, all the cases in the latter group had 15% or more acrosome-reacted sperm, whereas the parameter was widely distributed in the former group and some in this group had a decreased ratio. It would appear that a disturbance of the acrosome reaction is one of the causes of reduced fertility potential in normozoospermic males.

Acrosome-reacted sperm was examined in infertile and fertile males using the Acrobeads test. The Acrobeads score was significantly higher in fertile males than in infertile males with normal or abnormal seminal findings (p < .005 and p < .001, respectively). The Acrobeads score was 2 or more in all the fertile males, but 62% of the infertile males with abnormal seminal findings (p < .02). Therefore, a disturbance in the acrosome reaction is suggested to be one of the causes of decreased fertility potential. A high correlation was found between Acrobeads score and sperm motility (r = .46, p < .001) or motile sperm concentration (r = .51, p < .0001). The Acrobeads test, the results of which reflect the acrosome condition of the sperm, is useful in the assessment of sperm function related to fertility.