Fusome as a Cell-Cell Communication Channel of Drosophila Ovarian Cyst
In most animal species, female and male gametes are produced within clusters of germ cells which share a common cytoplasm through cell-cell channels. In Drosophila ovaries, these cells synchronise their divisions and specialise one cell of the cluster as the future egg. Both processes are organised by a germline-specific organelle of communication called the fusome. Untill recently, the fusome has remained largely mysterious despite a hundred years of research on its composition, formation and functions. Novel results have now suggested several molecular mechanisms to explain how the fusome synchronises the divisions by controlling cell-cycle regulators and how it determines and polarises the future egg by organising the microtubule cytoskeleton. Importantly, a structure similar to the fusome has been identified during Xenopus oogenesis, suggesting that it is widely conserved from invertebrates to vertebrates, and that it thus serves an essential function.