Figure 1. Expression of core appendage patterning genes in the head neurectoderm of Drosophila embryos.

Data are presented as maximum projections of confocal sections through embryonic procephalic neurectoderm of a stage 11 Drosophila embryo. (A) Schematic of the procephalic region of a stage 11 Drosophila embryo displaying subdivisions of the neurectoderm. Indicated are anterior, central, and posterior protocerebral and deuterocerebral regions of the head neurectoderm (adapted from (Younossi-Hartenstein et al., 1996)), as well as the mandibular (md), maxillary (mx), labial (lab), and first thoracic (T1) segments. (B) btd is transcribed mainly in the anterior protocerebral neurectoderm with a small region of expression in central regions. Also seen are antennal and maxillary segment expression outside the neurectoderm. The D-Sp8 transcription pattern is the same as btd in this region (data not shown). (C) Dll is transcribed in nearly the same neurectodermal pattern as btd at this stage. (D) dac is transcribed mainly in central and posterior protocerebral neurectodermal cells and overlaps with the posterior expression of Dll and btd. (E) hth is expressed in posterior protocerebral cells and deuterocerebral cells, overlapping with dac expression in its posterior expression domain. (F) Diagram indicating relative expression domains of Dll, btd, dac, and hth in the procephalic neurectoderm. Dashed arrow indicates general anterior to posterior orientation of the head neurectoderm.