Figure 2
From: Fluid viscoelasticity promotes collective swimming of sperm
Sperm orientation correlation length and cluster size increase with fluid elasticity. (a) The spatial correlation of sperm head orientation as a function of distance in standard medium (black lines), viscous 3% PVP (blue lines) and viscoelastic 0.7% PAM (red lines). Dashed lines are smoothed experimental data and solid lines are fitted data. (b) Spatial orientation correlation function exhibits an exponential decay. (c) Correlation lengths of sperm in different media. *p < 0.05 from non-overlapping 95% confidence levels, compared with standard medium. (d) Distributions of sperm cluster size in different media in log-log scale. 1 = single cell. Cluster size distributions follow a power-law function. (e) Mean cluster sizes of sperm in different media. ****p < 0.0001, compared to standard medium, from one-way ANOVA. (f) Mean correlation length plotted against mean cluster size. Linear regression shows a line with a slope that is significantly non-zero (p < 0.0001), and intersects the x axis at x = 1.0. Data derived from analyses of 5392 cells. Pearson r = 0.97. (g) Alignment coupling strength in different concentration of PAM solutions. *p < 0.05 from one-way ANOVA; s.e.m. are plotted, N = 10. (h) Coupling strengths and correlation lengths are highly correlated. Spearman r = 1 and p = 0.015. (i) Coupling strengths and average cluster sizes are less correlated with Spearman r = 0.81 and p = 0.39.
