Fig. 2. The SMs are underdivided in n2170sd animals. The M lineage for the hermaphrodite is shown in A [adapted from Sulston and Horvitz (Sulston and Horvitz, 1977)]. The time of postembryonic development is indicated on the left in hours and larval stages (L1-L4). The M blast cell divides in characteristic planes: d, dorsal; v, ventral; l, left; r, right; a, anterior; p, posterior. Subsequent divisions occur on the a-p axis. gfp reporters exist that mark each tissue type that differentiates from M and the green lines shown represent gfp expression from hlh-8::gfp in SM and its descendants. Vertical lines represent cells, and horizontal lines represent cell divisions. (B-E) Images are Nomarski/GFP merged micrographs of animals with integrated hlh-8::gfp. Dorsal is upwards, and anterior is leftwards. (B) Wild-type animals have 16 SM descendants (eight can be seen in this focal plane) surrounding the developing vulval opening (white arrowhead). The green on the dorsal side of the animal is due to intestinal autofluorescence and not GFP. (C) The SMs divide in nr2061 (–) animals and this image shows greater than the wild-type number of cells near the vulval opening. (D,E) The undivided SMs in n2170sd animals can be seen along the ventral length of the animal (white arrows). The animal in D is the same age as in B and C, based on vulval development, and has three undivided SMs. In older animals (E), the SMs still have not divided and continue to express hlh-8::gfp.
