Sexually dimorphic neurons in the terminalia of Drosophila melanogaster: I. Development of sensory neurons in the genital disc during metamorphosis.

The adult terminalia of Drosophila melanogaster males and females are sexually dimorphic. The sensory neurons that innervate the sex-specific bristles of the analia and genitalia arise within the genital disc during metamorphosis. Using antibodies that recognize peripheral neurons, I have followed the development of neurons in the female genital, the male genital and the shared anal primordium. Neurons form only in the expressed genital and anal primordium at the onset of the white prepupal stage. Two basic types of neurons differentiate in the genital disc; exteroreceptors that innervate the external bristles and enteroreceptors that innervate the internal reproductive organs. Within the genital disc, each structure has a sex-specific time during pupation when its neurons differentiate even when neurons are derived from homologous primordia. The data suggest that the sexually dimorphic arrangement of sensory neurons is a product of sex-specific neurogenesis.