EggFIG 7: Vulval cell patterning.

A. Establishment of vulval precursor cell (VPC) fates. Schematic, lateral view, showing the three known signaling events that establish primary, secondary, and tertiary vulval precursor fate among the midbody Pnp cells during early L3. (Based on Greenwald 1997; Sundaram 2004.)
B. Lineal origin of terminal vulval cells. Top Lineages of the VPCs. VPC primary, secondary, or tertiary fate is defined by the lineage pattern expressed by a given VPC. The plane of cell division is relative to the animal body axis. (T) Left/right; (L) anteroposterior; (N) no division; (S) fusion with hypodermal syncytium. The scale on the left indicates the larval stage of development and time post-hatching in hours (hr) at 20°C. The corresponding number of VPC progeny cells present at each step of the lineage is shown on the right. Bottom Arrangement of terminal vulval cells after completion of the lineage, dorsal view. A–F correspond to the adult vulval toroids (vuls) formed by the fusion of specific groups of terminal cells (depicted in EggFIG9). (Based on Sulston and Horvitz, 1977; Sternberg and Horvitz, 1986; Sharma-Kishore et al., 1999.)

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