FIG. 4.
Neuromuscular synapses mature normally in HSA::cre; gabpαf/− mice. (A and B) Whole mounts of diaphragm muscles from P21 control mice and HSA::cre; gabpαf/− mice were stained as described in the legend to Fig. 3. Neuromuscular synapses exhibit a branched, pretzel-like structure in control mice (A) or gabpα mutant mice (B). Furthermore, the sizes of myofibers are similar in gabpα mutant mice and control mice (A and B). (C) The density and total number of synaptic AChRs are similar in muscle from control mice (n = 4) and HSA::cre; gabpαf/− mice (n = 6). (D and E) Whole mounts of intercostal muscles from P21 control mice (D) and HSA::cre; gabpαf/− mice (E) were processed for in situ hybridization. AChR ɛ mRNA is concentrated in the central region of muscle from gabpα mutant P21 mice, similar to the case with control mice. (F) RNA from gastrocnemius muscles of P21 control mice (n = 3) or gabpα mutant littermates (n = 5) was reverse transcribed, and AChR ɛ gene expression was measured by quantitative PCR. Expression of AChR ɛ is similar in HSA::cre; gabpαf/− mice and control mice (P > 0.2). Scale bar = 10 μm for panels A and B or 200 μm for panels D and E. Error bars in C and F indicate standard errors of the means.