Figure 2. Fluorescence microscopy images of mature spermatozoa.

Spermatozoa were taken from the cauda epididymis of wild-type (A) and LKB1_SKO mice (B–D), and visualised by immunofluorescence. Tails were stained with an anti-tubulin antibody (red), acrosomes with an anti-acrosomal monoclonal antibody (green) and nuclei with DAPI (blue). Sperm from LKB1_SKO mice frequently show coiled tails (filled white arrows). In (D), the tail has formed a ‘lasso’-type structure around an abnormally shaped nucleus. Sperm nuclei from LKB1_SKO mice often lack acrososmes (open white arrow in B) as shown by the lack of green fluorescence at the anterior nuclear surface. Abnormal cellular debris is visible in LKB1_SKO samples, as indicated by asterisks in (C). Slides were viewed on a Leica TCS SP1 confocal microscope. Images are representative of at least three mice (Scale bar  = 20 µM).