The germarium is an assembly line for new egg chambers. Each ovary contains more than a dozen germaria. At the start of the assembly line in any single germarium are two germ line stem cells. A more detailed look at stem cell division reveals the two resulting cells are asymmetric in both function and size. The cystoblast continues along the line, undergoing four cycles of cell division to form a 16 cell cyst.
Ring canals maintain the connection among cells in the dividing cyst.
The single cell of cyst that contains the MTOC develops into the oocyte. Only the oocyte and will continue through meiosis, while the remainder will differentiate to become nurse cells for the presumptive oocyte. The nurse cell genome becomes polytene, a process in which DNA is replicated without cell division. To understand oocyte determination, one needs to ask how a particular cystocyte is singled out to acquire an active microtubule organizing center. Germ cells contain a spherical cytoplasmic structure called the spectrosome, which contains components of the sub-membrane cytoskeleton.