FIGURE 1

Development of neuromast patterning in the zebrafish anterior lateral line system from early larval to adult stages (3–22 mm SL). (A–A′) Summary schematic of patterning changes between 3 mm SL/7 dpf larvae and 22 mm SL adults. The number and size of canal neuromasts (blue) increase, and hundreds of superficial neuromasts (magenta) are added. Each canal line and superficial neuromast series found in the adult is labeled 1–13. (A) At 3 mm SL, the presumptive mandibular (MD) canal line (1), infraorbital (IO) canal line (2), supraorbital (SO) canal line (3), and otic series (4) are present. (A′) At 22 mm SL, nine additional lines of superficial neuromasts are present: the MD superficial line (5), which runs parallel to the MD canal line; the IO superficial line (6), which runs parallel to the IO canal; the SO superficial line (7), which runs parallel to the SO canal line; the MD series (8) at the anterior end of the MD canal; the nasal series (9) at the anterior end of the IO canal; the anterior pit line (10), which buds dorsally from O1; the hyomandibular superficial line (11); the dorsal opercular line (12); and the opercular line (13).  (B–E) Anterior LL neuromast pattern through ontogeny; e, eye. (B) Confocal maximum projections of the cranial region of a 3 mm SL specimen immunolabeled with Sox2 (magenta) and the nerve marker acetylated alpha‐tubulin (cyan), Scale = 200 µm. (C) Confocal maximum projections of the cranial region of a 10 mm SL specimen immunolabeled with Sox2 and acetylated alpha‐tubulin. (C′) Single channel split of the specimen in (C) showing the Sox2 label. Infraorbital (IO) canal neuromasts are labeled in cyan, and hyomandibular/mandibular (HM/MD) canal neuromasts are labeled in yellow. Scale = 200 µm. (D) Lightsheet maximum projections of the cranial region of a 22 mm SL young adult specimen labeled with Sox2. The image was processed with IMARIS. The SO canal boundaries are highlighted (yellow dotted line). Yellow asterisks indicate an example of “splitting” of a canal neuromast. Scale = 100 µm. (E) Close‐up of the supraorbital (SO) canal of the same specimen. The canal boundaries are highlighted (yellow dotted line), and canal neuromasts SO1*‐SO3 are indicated with white arrows and labeled. The SO superficial neuromasts are also indicated. Examples of non‐neuromast Sox2 expression are indicated by yellow arrows. Scale = 100 µm. (F–G) Quantification of neuromast patterning over ontogeny (3–22 mm SL). The region showing neuromast counts from 7–0 mm SL specimens is emphasized (gray rectangle). (F) Neuromast count versus Standard Length (mm) for (n = 10 each) of 3–10, 15, and 22 mm SL specimens. Values present in brackets denote standard deviation. (G) Neuromast count by line (total canal, IO superficial, MD superficial, opercular superficial, and SO superficial) versus Standard length (mm).