MaleSpicFIG 8: Lineal origin of spicule cells.

**α vs β and γ vs δ fates determined by positional cues (see MaleSpicFIG 9). Socket cells (SPso1-4L/R) of the L/R side fuse forming a 4-cell syncytium. Sheath cells (SPshD/V L/R) of the L/R side fuse forming a 2-cell syncytium (see MaleSpicTABLE 1). *Spicule neurons. (Adapted from Sulston et al., 1980; Chamberlin and Sternberg, 1994; Jiang and Sternberg, 1999.)