Figure 5.

Mature spermatid heads remain in a tight bundle attached to the testis wall during the coiling stage. (A), (B) Sets of time lapse images of the testis base, expressing the sneaky-GFP transgene [20], were projected together to show the relative movement of the acrosome bundles of a cyst inside the testis. Each frame is labeled with a specific false color as per the list shown in (B). The blue arrows and arrowheads point to the positions of acrosome bundles in the first frame while the white arrows and arrowheads indicate the final position. The arrows indicate the compacted set, which is likely to belong to the post-individualization stages, while the arrowheads indicate the acrosomes of the elongating/pre-individualization stage spermatids. (A) The compacted acrosome bundle (arrows) found near the base of the testis remain confined in the region as indicated by the positions of the blue and white arrow. Some acrosomes (green arrow) are occasionally found to move away from the bundle. This is considered to belong to the defective sperm that are lost during coiling. In comparison the acrosomes of the elongating spermatids (arrowheads) are loosely organized and move rapidly towards the testis base as evident from the positions of the blue and white arrowheads. (B) The mobility of acrosome bundles (blue and white arrows) near the base of the testis increased after 30 minutes of 5 μM vinblastine (vinb ) treatment. (See Additional files 2 and 4 for details.)