Comparison between miR-124 and miR-9 expression at late larval stage of B. floridae. Anterior to the left. Cross section scale bars are 25 μm. A, I: Side views of larvae with three to four gill slits. Scale bars: 250 μm. B, J. Anterior enlargement of specimens in A and I, respectively. Scale bars: 50 μm. C, K. Enlarged view of the neural tube of specimen in A and I at level of three dorsal ocelli (the first dorsal ocellus appearing during the development and located near the somite 5 is shown by arrows, the most anterior ones are indicated by arrowheads. Each differing from the first dorsal ocellus in being bicellular associations between a single neuron and a single pigment cell). Scale bars: 50 μm. D: Cross section through level d in B. E, F: Cross sections through levels e and f in C. L, M: Cross section through levels l and m in J. N: Cross section through level n in K. G, O: Detail of specimens in A and I at levels of the first dorsal ocellus (arrows). Scale bars: 50 μm. H, P: Cross sections through levels h and p in G and O, respectively.