Figure 2.

The upper four panels depict progressive stages in chromatin condensation during spermiogenesis (a: round spermatid, b: elongating spermatid, c: almost mature spermatid). Mature spermatozoa (d) have complete condensation, clear small uncondensed areas (asterisk) and the nuclear pocket (NP) near the neck region. Bars=1 µm. The two bottom drawings illustrate the relationship of DNA strands to histones (light blue, e) or protamines (red, f). Note the closer packing of DNA–protamine complexes.