Fig. 1

Neuromuscular junction analysis reveals differential vulnerability between cranial and abdominal muscles. a Confocal micrographs show neuromuscular junctions labelled with bungarotoxin (BTX, red) and antibodies against neurofilament and synaptic vesicle protein 2 (NF/SV2, green). Images are P21 Smn ^2B/- muscles (Adductor auris longus [AAL]; Auricularis Superior [AS]; Levator Auris Longus caudal and rostral bands [LALc, LALr]; External Oblique [EO]; Transversus Abdominis [TVA] and Rectus Abdominis [RA]. Control muscle is from P21 Smn ^2B/+ (control) TVA. Note increase in denervated endplates and pre-synaptic swelling and poor pre-synaptic elaboration and endplate maturation in abdominal (EO, TVA, RA) muscles compared to cranial (LAL, AS, AAL) and control muscles. Scale bar = 75 μm. b Bar chart (mean ± SEM) showing percentage of fully occupied endplates in cranial and abdominal muscles in Smn ^2B/- mice at P21. ***P < 0.001, ** P < 0.01, *P < 0.05 by Kruskal-Wallis test with Dunn’s Multiple Comparison Test in comparison to control (Smn ^2B/+ TVA)