Muscle Spindles in Gastrocnemius Muscle and TrkA/TrkC Staining in the Tibial Nerve at P0

<div><p>(A) NF-M (red) and S46 (green) immunostaining in cross section of gastrocnemius muscle at P0. There are no muscle spindles detected in double KOs.</p> <p>(B) NF-M (red) and S46 (green) immunostaining in parallel sections of gastrocnemius muscle at P0.</p> <p>(C) NF-M (red) and S46 (green) immunostaining in parallel sections of gastrocnemius muscle at E17. Double null muscles are mostly devoid of muscle spindles, except for one spindle-like structure detected (shown in inset, denoted by the asterisk).</p> <p>(D) Muscle spindles detected by DiI labeling through the DRG. Gastrocnemius muscle is sectioned at 40 μm thickness in parallel plane to the muscle fibers.</p> <p>(E) Muscle spindles detected by TrkC staining in cross section of gastrocnemius muscle at P0.</p> <p>(F) TrkA (red) and TrkC (green) immunostaining in the tibial nerve cross section at P0. TrkC-positive fibers are missing in <i>NT-3</i> KOs. Red-green overlap (yellow) is due to the thickness of the section and overlapping of red- and green-labeled (TrkA and TrkC) fibers present at different focal depths, rather than co-localization.</p> <p>Arrows indicate muscle spindles.</p> <p>Scale bar: 50 μm (A, B, D), 25 μm (C, E), 75 μm (F).</p>