Acrosome

**Definition:** The cap-like structure covering the anterior portion of SPERM HEAD. Acrosome, derived from LYSOSOMES, is a membrane-bound organelle that contains the required hydrolytic and proteolytic enzymes necessary for sperm penetration of the egg in FERTILIZATION.

**Tree numbers:** - A05.360.490.890.820.100 - A11.284.430.214.190.875.190.550.040 - A11.497.760.400.100