Fig. 1. Dynamics of bam expression. Schematic view of the germarium to demonstrate the dynamic pattern of bam mRNA and protein distribution. bam transcripts are undetectable in germline stem cells (GSCs) by RNA in situ hybridization but a small amount of Bam protein is produced and decorates the GSC fusome. In the cystoblast, bam mRNA accumulates to its highest levels. As cysts mature, the concentration of bam transcripts declines and are again undetectable in eight-cell cysts. During the period from cystoblasts through eight-cell cysts, Bam protein concentrations increase dramatically in the cystoplasm and expanding fusomes, reaching their highest levels in eight-cell cysts. Bam protein disappears rapidly from cystocyte cytoplasm once the 16-cell cyst forms.