Fig. 3. MSP-binding site distribution and expression of GFP::NMR-1 and VAB-1::GFP in the proximal gonad. (A) Fluorescein-labeled MSP (MSP-FITC) binds to oocytes and sheath cells of proximal gonads. In deconvolved mid-focal plane images, fluorescent intensity is enriched at the oocyte/oocyte interface. (B) A 3D reconstruction of the stack shows similar results. (C) The fluorescent intensity is high at membrane sites between oocytes even when the sheath cells are removed. (D) By contrast, MSP-FITC appears uniformly distributed around the oocyte plasma membrane in isolated oocytes. (E-G) In GFP::NMR-1-expressing gonads, GFP fluorescence is observed at the oocyte plasma membrane (E). Extensive co-localization with F-actin (F) is observed in the merged image (G). (H-J) VAB-1::GFP expressing gonads show a similar pattern of fluorescence. (K-M) GFP fluorescence is not observed in control gonads. (N,O) By focusing on the sheath membrane, GFP fluorescence is detected in the sheath of GFP::NMR-1-expressing gonads (N), but not in control gonads (O). Arrows indicate the sheath cells. All gonads are oriented as shown in Fig. 1A. DAPI is included in E-M. The VAB-1::GFP expression pattern has been reported previously (Miller et al., 2003). Scale bars: 10 µm.