Figure 2.

Anatomy of spermatozoa. A spermatozoon consists of three major components: head, midpiece, and tail. The sperm head is overlaid by a plasma membrane, and an acrosomal compartment containing enzymes to aid in fertilization. The nucleus, surrounded by the nuclear envelope, contains the compacted male genome. The head is connected to the midpiece by the connecting piece. The midpiece consists of the proximal centriole, the mitochondrial sheath, and an inner dense fiber structure. The tail points distally, is also covered by a plasma membrane, surrounding the structural axoneme.