Figure 7.

Configuration and extent of DTC processes. (A) Adult hermaphrodite germ line, 24 h past mid-L4. Each part of the panel is a projection of two confocal sections in adjacent focal planes from the same germ line. Green, GFP; red, anti-GLP-1; blue, TO-PRO-3. The DTC extends short processes that intercalate between and nearly surround germ cells in the first 2 rows along the distal-proximal axis. (B–F) Images are projections of confocal z-series. Genotype and reporter GFP indicated in figure. Green, GFP; pink, anti-PH3; blue, TO-PRO-3. Green triangle, proximal extent of extensive DTC contact; yellow circle, proximal extent of longest DTC process; diamond with dashed line, MR/TZ boundary. (B) +; qIs56 L4 germ line. (C) +; qIs56 adult germ line, 24 h after L4. (D) +; qIs56 adult germ line, 72 h after L4. (E–G) DTC process length does not change in mutants that affect the position of meiotic entry. (E) fbf-1(ok91); qIs56. (F) fbf-2(q738); qIs56. DTC maintains extensive contact with distal-most 4 rows of germ cells and extends processes up to 12 cell diameters in a wild-type background as well as in mutants that shorten (fbf-1) and lengthen (fbf-2) the mitotic region. (G) +; qEx319. Germline from animal carrying the lag-2::LAG-2::MYC construct. Green is anti-MYC, pink is anti-PH3, blue is TO-PRO-3. LAG-2::MYC fusion protein is found throughout the DTC and its processes. (H) Graph comparing position of MR/TZ boundary to extent of DTC cap and length of longest continuous process. DTC maintains extensive contact with distal-most 3 or 4 rows of germ cells (green square) and has no long processes in L4, extends processes ∼12 and 18 cell diameters proximal from the DTC body 24 and 72 h after L4, respectively. Although the DTC processes lengthen, the beginning of meiotic prophase occurs closer to the DTC body with age. Note that mitoses, as indicated by PH3 staining, can occur in germ cells that do not contact the DTC or its processes (L4 and 24 h). This is also apparent in older animals when individual z-slices are examined. Although the MR shortens, cell number does not decrease dramatically with age (see first section of Results). (I and J) Charts with data for wild-type at different stages (I) and mutants at 24 h after L4 (J).