Tubulin and microtubule-like structures in mammalian acrosomes

Immunofluorescence and electron microscopy were used to demonstrate the presence of tubulin and microtubule-like structures in rabbit and rhesus monkey sperm acrosomes. The distribution of tubulin within the acrosome appeared similar to the distribution of proteolytic activity, suggesting an association of proteinase with these structures. Electron microscopy of rhesus monkey sperm incubated in vitro demonstrated a progressive condensation of the acrosomal matrix into microtubule-like structure. A system of this type could explain the linear patterns of silver-proteinate staining in the pentration tunnel through the zona pellucida.