Overexpression of Cad99C^Scer\UAS.fl in the salivary glands under the control of Scer\GAL4^fkh.PH, in an otherwise wild-type background, results in a dramatic expansion of luminal width, with differences first visible during invagination and more obvious in late embryos. The apical domain of individual cells in Cad99C^Scer\UAS.fl-overexpressing salivary glands is expanded significantly, with the apical membranes extending deep into the lateral regions on the apical side. These cells also display increases in apical microvilli-like structures extending into the lumen, as well as in apical-membrane protruding deep into the regions between cells. Overall luminal length of Cad99C^Scer\UAS.fl-overexpressing salivary glands is not significantly different from wild-type, despite the apical expansion of individual cells.

Throughout embryogenesis, Cad99C^Scer\UAS.fl-overexpressing salivary glands exhibit irregular basal boundaries with indentations between individual cells, distinct from the smooth basal surfaces of controls. By late embryogenesis, several Cad99C-overexpressing cells have lost the typical columnar shape and are either cuboidal or round, with minimal contact between neighbors.

Expression of Cad99C^Scer\UAS.fl in the salivary glands under the control of Scer\GAL4^fkh.PH results in stretched adherens junctions and wider apical domains in each cell compared with wild-type, consistent with increases in apical domain size.

Expression of Cad99C^Scer\UAS.fl in the trachea under the control of Scer\GAL4^btl.PS results in apical membrane expansion and cell rounding, correlating with mislocalized Cad99C in the basal membrane.

Salivary gland cells expressing Cad99C^Scer\UAS.fl under the control of Scer\GAL4^fkh.PH reveal rounded basal surfaces and wider spaces between neighboring cells, indicating a loss of cell-cell contact nearly everywhere other than the septate junction.

Expression of Cad99C^Scer\UAS.fl in follicle cells under the control of Scer\GAL4^{Scer\FRT.Rnor\CD2.Act5C} induces a striking increase in the length of apical microvilli. These long cellular protrusions, which sometime exceed the apical-basal length of the follicle cells, project into the narrow space between follicle cells and oocyte. Very long extensions exhibit small knoblike dilatations. The vitelline bodies deposited between the overlong microvilli also appear enlarged.