Laminin and basement membrane-associated microfilaments in wild-type and mutant Drosophila ovarian follicles.

The localization of the extracellular matrix glycoprotein laminin was studied using polyclonal anti-laminin antibodies. The laminin patterns of the basement membranes of the muscular epithelial sheath that envelops the ovariole were conspicuously different from those of the basement membrane of the follicular epithelium. In the latter structure laminin was stained in a pattern of parallel stripes oriented perpendicular to the long axis of the follicle; microfilament bundles at the adjacent basal side of the follicle cells have the same orientation. At late vitellogenic stages the orientation of the microfilaments remained the same while the laminin stripes were no longer visible. The orientation of laminin and F-actin was abnormal in follicles of the egg-shape mutant kugel, which produces shorter and thicker eggs than wild-type flies. This phenotype might result from the disturbance of the normal circular microfilament and/or laminin pattern.