Fig. 4

Confocal projections showing Hox gene expression in rudiment-stage larvae of P. californiensis. Left panels show nuclear staining (propidium iodide, in yellow) as an overlay over transmitted light images. Larval anterior is to the left. Outline of the central nervous system indicated by blue dotted line (ns). Panel a shows additional features, such as epidermis (ep), gut (gt) with lumen in dotted line (both in red), and fibrous core of cerebral ganglia and lateral nerve cords (fb, gray shading). Right column shows transmitted light images showing the relative position of the nervous system with blue dotted line. Scale bar is 20 µm.