Figure 2

Oviduct epithelia display region-specific apical morphology and septate junctions are formed prior to mating. (A) Upper oviduct (unmated): This is the only region where two types of epithelia cells (light and dark) are observed. Both cell types display apical microvilli (MV) and are joined by an extensive septate junction (SJ; white and black arrows); Muscle (M). Higher magnification of SJ between light and dark cells (A') and SJ between two light cells (A"). Note that both SJs are covered by interdigitations (arrow) and septae are not visible, but intercellular space is filled with electron dense material. (B) Lower oviduct (mated): epithelia cells are joined apically by SJ (long arrow). Basolateral membrane (BL) gives rise to a labyrinth-like membrane which is joined laterally by spot adherens junctions (AJ; thick arrow). (B') Higher magnification of AJ; intercellular space (arrow) is filled with a filamentous material. (B") Higher magnification of SJ which is covered by interdigitations (arrow). (C) Lower oviduct (unmated): Apical membrane gives rise to brush border-like microvilli (MV); epithelia cells are joined laterally by a SJ (arrow). (C') Higher magnification of SJ. Note the apical position of SJ (arrowhead) and ladder-like arrangement of septae (arrow). (D) Schematic summary of cell-cell junctions: Different types of junctions are observed in different regions of oviduct, but no differences are observed between unmated and mated females. SSJ (smooth-like septate junction), PSJ (pleated septate junction), AJ (adherens junction), LO (lateral oviduct), CO (common oviduct). Bar equals: A (2 μm), A' and A" (500 nm), B (1 μm), B' (200 nm), B" (500 nm), C (1 μm), C' (100 nm).