miR-183 expression in B. lanceolatum and B. floridae. Anterior to the left and dorsal up in all whole mounts. Cross-sections are viewed from the anterior end of the animal. Scale bars are 50 μm for whole mounts and 25 μm for cross sections. A: Side view of a 72-h larva. B: Detail of the head region of larva in A showing expression in epidermal cells located in the most anterior tip of rostrum (arrow) and in dorsal wall of the posterior cerebral vesicle (arrowhead). C: Higher magnification of specimen in A with in focus labeled epidermal cells on the sides of the rostrum (arrows). D, F: Cross sections through the levels indicated by an arrow (D) and an arrowhead (F) in B, respectively. E: Cross section through level e in C. G: Side view of B. floridae larva. H: Enlargement of the specimen in G showing expression in epidermal cells of rostrum, cells of the dorsal posterior region of cerebral vesicle and in scattered cells of the neural tube (arrow).