Nvi-Lox4 expression pattern during Alitta virens development. The anterior end is to the right on all panels. All views are ventral. Asterisks mark a background. (A) Expression of Nvi-Lox4 at the nectochaete stage is weak (marked with arrowheads). (B, C) Expression of Nvi-Lox4 in juvenile worms (marked with arrow on panel B). On panel C, the metameric spots in each segment are a background in the epithelial glands. (D, E) Posterior part of the juvenile worm. (D) The worm was stained with To-Pro-1 (515/531). Expression of Nvi-Lox4 is noticeable only in the VNC surface cells, as internal expression domains are hidden by fluorescence. There is no expression in the ectodermal part of the GZ. (E) Posterior part of the juvenile worm, deep view. Nvi-Lox4 is expressed in the mesoderm. See text for details. GZ, growth zone; VNC, ventral nerve cord.