Although pharyngeal and valve cell intercalations in C. elegans occur when their apical surfaces are very small (Figure 7E), laminin can be detected at the midline of the polarized cyst and intestine after these primordia polarize (Figure 5E), and by electron microscopy extracellular materials are visible adjacent to the apical surfaces of cyst cells (our unpublished results). Here, LAMB2 is linked to cyst.