Figure 5
Expression of Nvi-ParaHox genes during formation of the adult digestive tract. (a-b) Expression of Nvi-Gsh. There are two cell types with Nvi-Gsh expression: one with very strong expression in separate, probably basal cells (a, b), and an anterior to posterior double gradient of expression in the endodermal layer of the posterior half of the intestine (a). That is, expression is low at the anterior of the domain, gradually increases to a peak in the center of the domain, then decreases again towards the posterior. (c, d) Expression of Nvi-Xlox. Expression in the epithelial layer occurs along the whole midgut (c) except at the posterior (d), where distinct Nvi-Xlox positive cells are visible. (e, f) Expression of Nvi-Cad. There is an antero-posterior gradient of Nvi-Cad expression in the posterior half of the gut, with expression increasing more posteriorly (e). (f) Three posterior domains of Nvi-Cad expression: midgut (white arrow), growth zone (white arrowhead), and pygidial cirri (black arrowhead).