Figure 1.

Background on C. elegans hermaphrodite germ line. (A) Schematic of adult hermaphrodite germ line. Somatic DTC, red; mitotic region, yellow; pachytene region, green; oocytes, pink; sperm, blue. Somatic tissues other than DTC are omitted for simplicity. (B) The adult mitotic region (MR). Above, extruded gonad stained with actin antibodies to outline “cell” boundaries. Below, diagram of actin-stained gonad, color-coded as in A. Transition zone, TZ. The germline MR extends from the distal end (arrowhead) to the distal edge of the transition zone (dashed line). Most germ “cells” are located peripherally and are connected by a cytoplasmic bridge to a cytoplasmic core running the length of the germline tissue (asterisk; Hirsh et al., 1976); the germ cells are technically part of a syncytium, but are referred to as “cells” because they are partially enclosed by membranes and because mitoses are not synchronized. Germ cell position is determined by counting cell diameters along the distal-proximal axis (D/P axis, numbers shown above lower diagram). The transition zone is dominated by meiotic prophase nuclei (Crittenden et al., 1994; Dernburg et al., 1998; Hansen et al., 2004a). We define the boundary between the MR and TZ by the point at which multiple germ cells acquire the crescent-shaped DAPI staining within their nuclei that is typical of early meiotic prophase (Eckmann et al., 2004). (C) Postembryonic germline development. Animals are outlined in gray; color coding as in A. L1–L4, first to fourth larval stage. Adult (24 or 96 h), adult 24 or 96 h past mid-L4; #GC, total number of germ cells. Approximate germ cell number for each developmental stage is listed at right.