Al-Abdominal-B ( Al-Abd-B ) expression. Embryos are oriented with the anterior to the left unless otherwise noted. (A) Ventral view of early Al-Abd-B expression. (A) DAPI image of the embryo in A. (B) Lateral view of the embryo in A. (B´) DAPI image of the embryo in B. (C) Ventral-lateral view of the embryo in A and B with anterior towards the top of the page, showing Al-Abd-B in the opisthosoma. (D) Close-up image of Al-Abd-B expression in the opisthosoma in B. (E) Al-en expression in the opisthosoma at the same stage as E. (F) Ventral view of a later staged embryo showing the clearing of Al-Abd-B from the Te. (G) Lateral view of the embryo in J. (H) Anterior-ventral view of the embryo in F and G showing strong Al-Abd-B expression in the anterior opisthosoma (arrows). (I) DAPI image of the embryo in H. (J) Ventral view of a later-stage embryo showing that Al-Abd-B expression has cleared from the Te. (J´) DAPI image of the embryo in J. (K) Lateral view of the embryo in J showing the restricted ‘spot’ of Al-Abd-B expression in the opisthosoma. (K´) DAPI image of the embryo in K. (L) Close-up of Al-Abd-B in the opisthosoma of an embryo approximately intermediate of B and G, showing earlier, broad Al-Abd-B expression. (M) Close-up of the opisthosoma showing Al-Abd-B in the same embryo in G. As the caudal bend progresses, Al-Abd-B expression clears from the Te and becomes restricted to O2. (N) Close up of Al-Abd-B in the opisthosoma of the embryo in K showing the further restriction of Al-Abd-B . Scale bars in A´, B´, J´ and K´ are 50 μm. See text for details. Ch, chelicerae; DAPI, 4′,6-diamidino-2-phenylindole; L1-L3, first through third walking legs; O1-O2, first and second opisthosomal segment; Pp, pedipalps; Te, telson.