Fig. 7. Effect of gradients of various stimulants on sperm accumulation. (A) Representative images of mouse spermatozoa from Tg mice showing sperm accumulation around the tip of a glass microcapillary containing 50 mM lyral or buffer. Scale bar, 100 µm. (B) Time course of spermatozoa accumulation in a 200-µm radius circular area around the tip of the microcapillary. Images are representative of six independent experiments for lyral and three for buffer. The graph shows the average numbers of sperm within the accumulation area as a function of time after the ejection of lyral (filled squares) or buffer (empty squares) (± s.e.; buffer, n=4; LY, n=6). A significant difference was observed between lyral and buffer after 4-7 (P<0.01) and 8-10 (P<0.05) minutes. (C) The numbers of Tg and wild-type spermatozoa attracted toward gradients of buffer, 50 mM lyral (LY), 50 mM dihydromyrcenol (DM), 50 mM bourgeonal (B), 10x concentrated K8.6 (K8) or 10-mM 8-Br-cAMP (cAMP). The graph shows the number of spermatozoa that accumulated in the 200-µm radius circle around the tip of each microcapillary. The numbers in parentheses represent the number of experiments performed for each reagent. ^*, P<0.05; ^**, P<0.01 (Student's t test, ± s.e.).