Fig. 3. Lateral Achaete expression is lost in SoxNeuro mutant embryos. Late stage 8 (A,B) and stage 9 (C,D) whole-mount views of wild-type (A,C) and SoxNeuro^U6–35 (B,D) embryos stained with anti-Achaete. In wild-type embryos, Achaete is expressed in proneural clusters of five to seven cells that give rise to the medial MP2 and NB7-1 and the lateral NB3-5 and NB7-4 neuroblasts. In SoxNeuro^U6–35 embryos, Achaete protein is undetectable laterally in 70% of rows (white arrowhead); however, Achaete is still observed in 80% of rows medially (white arrow); asterisk in D shows absence of Achaete in one NB7-1 neuroblast. (E) Achaete expression is greatly reduced in both medial and lateral columns in SoxNeuro^U6–35. The SoxN^U6–35/SoxN^U6–35 embryo to the right shows a much lower level of Achaete expression than its SoxN^U6–35/Cyo sibling of the same stage from the same staining reaction.