Intercellular bridges (ICB) are formed at the end of every cell division. In somatic cells they are transient structures and quickly abscised, resulting in formation of two daughter cells. In germ cells, however, the ICB structure is stabilized and the daughter cells are tethered together in a syncytium with a continuous cytoplasm. Synchronous differentiation of hundreds of spermatogenic cells within a syncytium is considered one of the outcomes of ICBs and the intercellular, or syncytial, molecular traffic that they enable. Other hypothesized functions of ICBs include compensation of chromosome dosage in post-meiotic haploid cells, synchronization of spermatogenesis, and sharing of essential signals and mRNAs within the syncytium. Stabilization of the ICBs is associated with a differentiation commitment in the male germline, and all spermatogenic cells develop in syncytia until the point of spermiation when mature elongated spermatids are released from the seminiferous epithelium as single cells. Spermatogenic cell syncytia are stable, but they occasionally break and do not reach their theoretical maximum size. On the contrary, ICBs of spermatogonial stem cells (SSCs) are highly unstable, and SSCs actively interconvert between single-cell and short syncytial states. ICBs are dynamic structures and they undergo changes in architecture, protein composition and diameter during the course of spermatogenesis. The fundamental importance of ICBs and ring canals for male germ cell maturation is underlined by the fact that they are formed during spermatogenesis in diverse organisms, and lack of ICBs results in azoospermia and male infertility.