Figure 5.

 Expression of Dlg during oogenesis. (a) Western blot of ovarian proteins probed with Dlg sera. Three polypeptides of 91, 100, and 102-kD are detected (arrowheads). (b) Ovarian tissue probed with Dlg sera and visualized by confocal microscopy. Dlg is expressed in germ cells and follicle cells starting in the germarium [where the germ cell cyst becomes ensheathed by follicle cells in region II; oogenesis is reviewed in Spradling (1993); cell types are labeled in Fig. 1]. Dlg protein expression continues in both cell types throughout the growth stages of oogenesis, as the germ cell cyst expands and the follicular epithelium increases from ∼40 cells at s1 to 650 cells at s6. Dlg staining is detected in both the cytoplasm and membrane. Staining is enriched in membranes at sites of contact between germ cells (c, arrows), and sites of contact between follicle cells (d, arrows). Following cessation of follicle cell division at s6, Dlg protein levels dramatically decrease in germ cells during s8–s10 (b), a migratory phase when follicle cell populations move to the oocyte (see also Fig. 1).