Fig. 6.

Confocal and electron microscopy images of NMJs from newborn and adult. Confocal microphotographs from wild type (WT) and knockout in nPKCθ (KO) NMJs at neonatal postnatal 4-day (P4, polyinnervated NMJs), postnatal 8-day (P8, monoinnervated NMJs) and adult were stained for AChRs (red) and axons and nerve terminals (neurofilament-200 protein in green). The selected examples of polyinnervated and monoinnervated NMJs from developing WT and KO muscles (P4, P8) show differences in the pre- and postsynaptic components that are in accordance with the quantitative measurements of the cluster morphology. Scale bars: 10 μm. The ultrastructure images of the KO NMJs during development and in the adult have the same structure than NMJs with comparable levels of maturation in WT muscles at P3, P6, P13 and adult. The NMJ from a P3 KO muscle shows the coexistence of several nerve terminal boutons (marked by asterisks in the drawing at the right of the picture) on a poorly defined, low-density, postsynaptic membrane without gutters. The NMJ from a P6 KO muscle shows an intermediary stage of axon separation. The NMJ from a P13 KO muscle shows advanced gutter formation and nerve terminal segregation and elimination. Nerve terminals (marked with # in the accompanying drawing) are engulfed by Schwann cell processes that also contain membrane debris. The right column shows drawings in which the three cellular components of the NMJ (axon terminal, Schwann cells and postsynaptic membrane density) have been delineated. Scale bar: 200 nm. Reproduced with permission from Lanuza et al. (2010) and Besalduch et al. (2011).