Fig. 6. (A-D) Comparison of invagination sites in Cupiennius salei and Pholcus phalangioides. Both embryos were stained with phalloidin-rhodamine. (A) Confocal micrograph of a flat preparation of a Cupiennius salei embryo at 200 hours. The ventral neuroectoderm has developed all 30 to 32 invagination sites. (B) Confocal micrograph of a flat preparation of a Pholcus phalangioides embryo. Despite the fact that the walking legs are longer than those of the Cupiennius embryo shown in A, the Pholcus embryo seems to be somewhat younger because the opisthosoma has not developed all invagination sites yet. (C) Invagination sites of the third opisthosomal segment of Cupiennius at 190 hours. There are six rows of invagination sites at this stage. The arrowheads point to the two anterior most lateral invagination sites. (D) In the third opisthosomal hemisegment of a Pholcus embryo at a stage comparable with the Cupiennius embryo shown in C, six rows of invagination sites can also be counted. The arrowheads point to lateral invagination sites of the hemisegment, which are located at similar positions in Cupiennius and Pholcus. Ch, cheliceral segment; ped, pedipalpal segment; l1 to l4, walking legs 1 to 4 (corresponding to prosomal segments 3 to 6); o1 to o5, opisthosomal segments 1 to 5. Scale bars: 200 µm in A,B; 100 µm in C,D.