Figure 6. Model for the specification of new tegumental cells from neoblasts.

Neoblasts (magenta cells) expressing nanos2 and zfp-1 specify large numbers of tsp-2⁺ cells. Some fraction of tsp-2 cells express zfp-1–1. Within this tsp-2 compartment are cells that extend cytoplasmic projections ultimately fusing with the tegumental syncytium. Loss of zfp-1 function results in a general differentiation defect (i.e. loss of both tegument progenitors and gut cells) whereas loss of zfp-1–1 function results in a specific loss of tsp-2⁺ cells responsible for replenishing the tegument. In both cases, depletion of tsp-2⁺ cells causes a reduction in the total number of tegumental cell bodies.