Keep Your Head Attached: The Sperm Connecting Piece

The sperm neck, or connecting piece, connects the head to the more distal tail regions.It is composed of two centrioles (proximal and distal) and specific pericentriolar cytoskeletal structures surrounding them: basal plate attached to the nucleus, capitulum, and striated (or segmented) columns continuing into the outer dense fibers.Together, these structures form the head-tail coupling apparatus of the spermatozoon.In mammals, the distal centriole undergoes a profound structural modification which allows efficient transmission of the tail movements to the head.Mutations in genes encoding neck cytoskeletal proteins lead to separation of the head from the tail, acephalic spermatozoa, and infertility.