During gastrulation, expression is elevated in the invaginating cells of the ventral and cephalic furrows. At stage 11 all central nervous system and peripheral nervous system precursor cells express high levels of sktl . This suggests that the two genes may share common regulatory elements and raises the question of whether they interact during nervous system development. In the leg disc expression is ubiquitous and uniform. In the wing disc, expression is elevated in the precursors of the anterior wing margin sensory organs and along the anterior-posterior axis.
Expression is very low or absent along the dorso-ventral axis.
In the eye disc, expression is elevated in the row of cells anterior to the morphogenetic furrow from which the R8 photoreceptors will differentiate. In the third instar larval brain, sktl is expressed widely but not ubiquitously. Adult During oogenesis , sktl expression is first observed in region 2 of the germarium. At this stage, sktl appears to be expressed in a subset of cells building the different cysts. In egg chambers of stagee S1-S14 strong expression is observed in the oocyte.