Parvalbumin distribution in the musculature of the pharyngo-oesophageal segment

The composition and size of muscle fibre types in the hyopharyngeus (HP), t hyropharyngeus (TP), cricopharyngeus (CP) and cervical oesophageal muscle ( CE) from 6 normal adult cats were investigated using parvalbumin (PA) immun ohistochemistry. Fibre types I. IIA and IIB were identified in all muscles, tip and TP revealed predominance of type II fibres (74.8% and 75.2%, respe ctively), 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 typ e II (23.9 mu m) than in type I fibres (21.7 mu m). The results seem to ref lect the physiological features of each muscle, i.e. short rapid contractio ns of HP and TP, sustained contraction of CP and slow peristaltic movements of CE.