Fig. 8. Model for specification and patterning of the C. elegans AB-derived epidermis. elt-1 is required to specify all major epidermal cells. A set of factors, including elt-5/6 and an unknown factor (X), directs some epidermal cells to become seam cells by activating partially redundant sets of nuclear hormone receptors and perhaps other transcription factors. elt-5/6 repress elt-3 expression in seam cells. We hypothesize that ELT-3, together with another factor (Y), specifies a non-seam fate. No information is available for how syncytial versus P cell fate is apportioned between the group of non-seam epidermal cells.
