Connecting piece

The connecting piece, or neck region, of spermatozoa connects the sperm head to the flagellum. It is formed around the sperm centrioles after attachment to the nuclear membrane during spermatogenesis. The formation of the connecting piece is initiated by the proximal centriole, resulting in the embedding of the centrioles in nine longitudinal segmented columns and the capitulum. The latter links the structure to a region referred to as the implantation fossa on the surface of the sperm nucleus. The connecting piece is essential for the connection between the sperm head and the tail, ensuring that both do not rip apart during progressive motility of the sperm, and then controling transfer of the sperm nucleus to the oocyte upon fertilization.

The connecting piece can be seen at the border between the sperm head and the flagellum, sometimes appearing like a plate-like structure upon which the nucleus rests.

Read more about the connecting piece as a substructure of sperm.