toe transcript is expressed in both male and female genital discs of third instar larvae. Expression is more extensive and at a higher level in female than in male discs.

toe transcripts are first detected at embryonic stage 9 in the salivary gland precursor and a small group of cells in the dorsal head. The salivary gland precursor expression persists through embryonic and larval development. At stage 10, transcripts are detected in the posterior spiracles and in a cluster of cells at the anterior edge of each thoracic and abdominal segment. By stage 12, expression is observed in the larval antennal organ and the leg disc primordium. In later stages, transcripts are found in the presumptive eye-antennal imaginal disc. In larvae, transcripts are observed at multiple sites. They are present in the medial and distal regions of the antennal disc and anterior to the morphogenetic furrow in eye discs in a narrow domain of cells that straddles the dorsal-ventral boundary. In wing discs, transcripts are expressed broadly in the notal region and in two discrete regions in the presumptive wing. toe transcripts are also found in leg discs and in anterior duct cells of the salivary gland. This pattern of expression is nearly identical to that of eyg and differs mainly in the persistance of expression in the salivary gland precursors.

toe transcript is detected in the anterior of early larval eye discs and is strongly expressed dorsally and anterior to the morphogenetic furrow in late eye discs. Expression also occurs in the central region of antennal discs.