Scanning electron microscope observations also revealed that the subneural apparatuses of the circular muscles consist of cup-like depressions with some junction folds. In contrast, those of the longitudinal muscles are
characterized by gutters with numerous slit-like folds.
Although no differences have been observed between the
NMJs of the two muscle layers of the mouse esophagus by
transmission electron microscopy [24], it is not certain if
this discrepancy is related to species differences.