Histochemical fibre types in human extraocular muscles, an investigation of inferior oblique muscle

Publisher Website
Google Scholar
Abstract
In order to test histochemical fibre types in human extraocular muscles, 2000 fibres from 5 inferior oblique muscles were examined in serial sections for myosin ATP-ase following preincubation at pH 4.3, menadione-linked alpha-GPD and NADHTR activity. In ATP-ase 4.3, ±15% of fibres in central and peripheral areas stained dark, the other fibres were slightly stained or unstained. Nearly all fibres with high activity in ATP-ase 4.3 had type I-like histochemical characteristics with high or very high NADHTR activity and low alpha-GPD activity. Fibres with low activity in ATP-ase 4.3 had a spectrum-wide variation in activity of NADHTR and alpha-GPD and could be divided into 3 subtypes with IIA, IIB and IIC-like characteristics. The histochemical profile of the fibres with type IIC-like characteristics differed from that of type IIC fibres in other skeletal muscles, by a lower ATP-ase 4.3 activity. In the central areas all 3 subtypes were more or less equally represented. In the peripheral areas most fibres with low ATP-ase 4.3 activity belonged to the IIC-like subgroup.