FIGURE 3

FSNs exhibit a variety of soma morphologies. (A) The four main FSN soma morphologies clockwise from top left: small spherical hindbrain (HB), small teardrop HB, rounded HB with dorsal projection, and a classic dorsally located RB with its dorsoventrally compressed shape resulting in elongation along the anteroposterior axis. The three hindbrain morphologies are apparent across cells associated with myomeres two and three. (B) FSNs are distributed across myomeres two through five, and they show no significant trends in soma size or distribution patterns across the anterior to posterior axis within any of these myomeres. FSNs exhibit no trends with regard to the hindbrain/spinal cord transition area (indicated in orange). Negative numbers are consistent with a hindbrain location, and positive numbers indicate a spinal cord location. Most of the cells innervating the fin are found in myomere three. Anterior is to the left, dorsal is up in (A). Scale is 25 microns in (A).