Among epidermal cells in the tail, efn-4
::gfp was expressed in Rn.a descendants but not in other tail epidermal cells. Expression was first detected in Rn.aa and Rn.ap cells, and expression increased in strength in their descendants. Expression levels among descendants of the same Rn.a cell were similar. Expression was strongest and most frequent in descendants of R2.a and R6.a, intermediate in strength and frequency in R4.a, R5.a, and R7.a, and absent from R1.a and R3.a; expression was not scored in R8.a and R9.a descendants because it was weak and highly variable between individuals.