Analysing a large number of different skeletal muscles, we demonstrated that in human skeletal muscles only three MHC genes are expressed, i.e. Beta-slow/1, 2a in 2x, and that recenly indetified gene coding for the fastest MHC isoform, i.e. 2b, is not expressed. These findings contribute to better knowledge of human skeletal muscle. Analysing the influence of different factors (cell line, innervation pattern, thyroid hormon level in blood) on MHC expression, we found that the slow soleus muscle of the rat, transplanted into the fast extensor digitorum longus muscle and reinnervated with its nerve, is able to transform to a fast muscle. However, the extend of transformation depended on the thyroid status of the animals; while the transformation was enchanced in hyperthroid rats, it was attenuated in hypothyroid rats. Comparing the results of tensiomyography ,i.e., the displacement of the muscle belly following a DC stimulation, and histochemical composition of different human muscles, we have confirmed the validity of tensiomyography as an uninvasive method which provides an insight into the volume share of slow muscle fibres within a muscle. We have described and quantified histochemical and immunohistochemical characteristics in control rat extraocular muscles and established changes in regenerated muscle after marcaine injection as well as in the recoved muscle following application of botulin A toxin. Introducing unbiased sampling design and design based stereological methods in the quantification of nuclei and satellite cells, we have pointed out the questionable reliability of the data on the frequency and dynamic nature of satellite cells, published so far. Further, we have confirmed that the frequeny of satellite cells in human muscles declines with ageing We have introduced a combined fluorescent staining that demonstrates capillaries and muscle fibres in thick sections of skeletal muscle tissue, simultaneously. The staining clearly distinguishes capillaries from the surrounding tissue in healty as well as in pathologically changed muscle. It enables threedimensional morfometrical measurements and provides a complex insight into the relationships between the structure of the capillary network and muscle fibres, which is important for understanding the mechanisms controlling tissue remodelling.