Figure 4.

Localization of Pax-Cam mRNA by in situ hybridization. (A) Photomontage showing Pax-Cam expression in scattered transectodermal cells in a pear-shaped planula larva. These cells are more abundant at the aboral (a) than the oral (o) end. Arrows identify some of these strongly expressing ectodermal cells. The line of white dots marks the basement membrane separating ectoderm from gastroderm (endoderm). Staining of occasional cells in the gastroderm is believed to be nonspecific. (B) Two cells with nuclei (n) midway across the ectoderm appear to project to a clump of expressing cells on the basement membrane. The message is excluded from the nuclei. (C) A single labeled cell with a basal nucleus (n) projects across the ectoderm. (Bars = 100 μm for A and 10 μm for B and C.)