Parvalbumin Distribution in the Musculature of the Pharyngo-oesophageal Segment.

The composition and size of muscle fibre types in the hyopharyngeus (HP), thyropharyngeus (TP), cricopharyngeus (CP) and cervical oesophageal muscle (CE) from 6 normal adult cats were investigated using parvalbumin (PA) immunohistochemistry. Fibre types I, IIA and IIB were identified in all muscles. HP and TP revealed predominance of type II fibres (74.8% and 75.2%, respectively), whilst CP and CE showed predominance of type I fibres (72.6% and 82.2%, respectively). The mean diameter of narrow fibres was greater in type II (23.9 μm) than in type I fibres (21.7 μm). The results seem to reflect the physiological features of each muscle, i.e. short rapid contractions of HP and TP, sustained contraction of CP and slow peristaltic movements of CE. [ABSTRACT FROM AUTHOR]