Fig. 2. Representative results of high-throughput, whole-mount in situ hybridization. (A-C) Probe identity corresponding to the images is given from top to bottom with each clone ID in parentheses as follows. (A) Gene expression patterns within the nervous system of S. mediterranea: synaptotagmin (H.6.7h); quinoid dihydropteridine reductase (H.9.5b); pax6 (H.109.7h) and degenerin (H.112.3c). (B) Gene expression patterns in organ systems: gastrovascular system (D.14; unknown function), dorsal epithelium (H.7.1e; gp25L/p24 family), excretory system (H.14.9d; carbonic anhydrase); and pharynx (H.14.11f; unknown function). (C) Gene expression in discrete cell types: matrix metalloproteinase (A115) in central secretory cells; epithelial cells (H.12.11a; intermediate filament); subepidermal marginal adhesive gland cells (H.1.3b; zonadhesin); and free-mesenchymal cells (neoblasts) expressing piwi (H.2.12c). (D) Ventral view (left) of clone H.8.1f (unknown function), and lateral view of the same specimen (right) demonstrate a dorsoventral segregation of differentiation. The red asterisk indicates the position of the pigmented photoreceptor. Anterior is to the left in all panels.