Fig. 1
From: Mouse models of SMA show divergent patterns of neuronal vulnerability and resilience
NMJ loss is more severe in muscles innervated by cervical, thoracic and upper lumbar regions of the spinal cord in Smn2B/− mouse model at P16. A–C Representative confocal images showing NMJs labelled with antibodies against NF (green) and SV2 (green) and BTX (magenta) staining in a control muscle (Smn2B/+; gracilis), a vulnerable Smn2B/− muscle (transversus abdominis) and a resistant Smn2B/− muscle (lumbricals), respectively. Pink arrowheads indicate fully occupied endplates, yellow arrowheads show partially innervated endplates, and blue arrowheads indicate vacant endplates. Scale bar: 25μm. D Bar charts showing the quantification of percentage of full, partial and vacant endplates in Smn2B/− mice in all investigated muscles. The muscles are displayed in order of their innervation from the cranial nerves and spinal cord segments, starting at the top with the muscles innervated by cranial nerves V (CN V) and VII (CN VII), followed by the muscles innervated from nerves arising from the cervical spinal cord and ending at the bottom with the muscles innervated by nerves arising from the lumbar spinal cord. The spinal cord segments that supply nerve innervation to the analysed muscles are indicated beside the respective bars. A high level of NMJ loss was visible across the muscles that are innervated by the nerves from cervical, thoracic and upper lumbar spinal cord segments. This pattern suggests that NMJ pathology starts at the centre of the spinal cord. n= 3 in IC and n=4 in all other muscles for Smn2B/− mice. Error bars represent mean ± SEM. E Schematic diagram of the relationship between location of spinal cord segments and the anatomical location of the muscles innervated by the nerves arising from the indicated spinal cord segments, starting with the head muscles. Colours are for illustrative purposes only