Fig. 7. (A-D) Expression pattern of the proneural gene CsASH1 and the neurogenic genes during the second phase of neurogenesis. Whole-mount in situ hybridisation; anterior is towards the top. (A) The proneural gene CsASH1 is re-expressed in the apical neuroectderm after the process of invagination is completed. (B) CsDelta1 is still expressed in a subset of the invaginated cells. Transcripts are visible in about 7 axon fascicles per hemisegement (arrow). (C,D) CsDelta2 (C) and CsNotch (D) are uniformly expressed in the neuroectoderm (arrows). 11 to 14, walking legs 1 to 4. Scale bar: 200 µm.