Fig. 3. Expression of Pax6A mRNA in an intact planarian, as detected by whole-mount in situ hybridization. (A) Dorsal view of GtPax6A expression in G. tigrina. (B-G) Anteroposterior sequence of some representative transverse cryosections of whole-mount depicted in A. GtPax6A is expressed in the cephalic ganglia and the nerve cords. Presence of GtPax6A transcripts can also be observed in the lateroposterior region, close to the dorsoventral border. (H) Nomarski view of a higher magnification of a transverse cryosection of the whole-mount in A, showing the localization of GtPax6A-labelled cells (arrowheads) in the lateroventral marginal region, close to the eosinophilic secretory cells (arrows). Scale bars: 0.5 mm.