Quantitative analysis of the size distribution of target- and targetoid fibres employing the method of Daeves and Beckel for mixed distributions.

An analysis of frequency distribution is performed in 250 target and targetoid fibres each from the anterior tibial muscle of a case with rapidly proceeding denervation atrophy. Following plane measurements on cross sections the size data were analysed according to the method of Daeves and Beckel [1] for mixed distributions. Three homogeneous normally distributed populations could thus be extracted from the mixed distributed sample. The largest population represents target fibres with a normal size range, while the second one encloses hypertrophic fibres, and the third and smallest one consists of fibres ranging within atrophic size limits. These findings support the previous presumption that targets predominantly occur in fibres of normal size and can therefore be regarded as manifestations of an early stage of denervation atrophy. The targetoid fibres, on the contrary, are of an atrophic size by 84%, while only a small population of about 15% contains targetoid fibres of a normal size on cross section.