Fig. 1. Rotation of genitalia and spermiduct looping in wild-type and spin males. (A) Scanning electron micrograph (SEM) of a wild-type male abdomen (ventral view; posterior is upwards), showing the position of the anus and penis. The direction and extent of genitalia rotation is schematized by a looping arrow (bottom right). (B) Schematic view of a wild-type abdomen showing the internal looping of the spermiduct around the gut, after clockwise rotation of the genital plate. (C) SEM of a spin^GAL4/Y; UAS-Fas2 male showing complete rescue of rotation. (D-F) SEM of representative spin males showing varying degrees of rotation. (G,G') Dissected wild-type abdomen and its schematic representation showing the rightward looping of the spermiduct. (H,H') Dissected spin male (similar to E), and its schematic representation showing an under-rotation phenotype. sp, spermiduct; g, gut; p, penis.