| 1. |
- Henriksson-Larsén, K., et al.
(författare)
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Distribution of different fibre types in human skeletal muscles : I. Method for the preparation and analysis of cross-sections of whole tibialis anterior
- 1983
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Ingår i: The Histochemical Journal. - 0018-2214 .- 1573-6865. ; 15:2, s. 167-178
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine whether small biopsy specimens are representative of the whole human skeletal muscle or whether the different fibre types are unevenly distributed at different depths of the muscle. Ten micrometre thick cross-sections of whole human tibialis anterior were prepared using LKB PMV Cryo-Microtomes with a stroke length of 160 to 480 mm and the sections were stained for myofibrillar ATPase according to a modified procedure. The total and relative number of different fibres (Types 1 and 2) was determined in every 9th mm2 of the section. The data obtained were analysed by means of a computer program, which allowed assessment of bivariate data in the form of contour plots. The total number of fibres varied greatly between individuals (from 96 000 to 162 000; five individuals). The relative number of different fibres varied systematically in all individuals as a function of depth in the muscle. There was a gradual, often dramatic, relative increase in Type 2 fibre occurrence from the surface of the muscle (about 10--25%) towards the deeper regions (30--50%), the maximum being approximately along a line slightly posterior to the middle of the muscle. Additionally, superficial peaks were seen in places. In conclusion, the fibre type distribution in the tibialis anterior is not random. These results point to the importance of defining biopsy depth
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| 2. |
- Lexell, Jan, et al.
(författare)
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Distribution of different fiber types in human skeletal muscles : effects of aging studied in whole muscle cross sections
- 1983
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Ingår i: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 6:8, s. 588-595
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Tidskriftsartikel (refereegranskat)abstract
- The effects of aging on the total number and size of fibers, and the proportion and distribution of type 1 (slow twitch) and type 2 (fast twitch) fibers were studied in cross sections (15 mu thick) of autopsied whole m. vastus lateralis from two age groups. Each group consisted of six, previously physically healthy males (mean age 72 +/- 1 years and 30 +/- 6 years, respectively). The size of the muscles of the older individuals was 18% smaller (P less than 0.01) and the total number of fibers was 25% lower (P less than 0.01) than those of the young individuals (mean number 364,000 +/- 50,000 vs 478,000 +/- 56,000). There was, however, no significant difference in the mean fiber size (indirectly determined) or the proportion of the two fiber types, though a preferential reduction in type 2 fiber number in the aged individuals was seen. The relative occurrence of the fiber types at various depths in the aged muscles was found to be more even than in muscles from the young individuals. The results suggest that the aging atrophy in m. vastus lateralis, at least up to the age of 70, is primarily the result of a loss of fibers.
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| 3. |
- Lexell, Jan, et al.
(författare)
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Distribution of different fibre types in human skeletal muscles : 2. A study of cross-sections of whole m. vastus lateralis
- 1983
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 117:1, s. 115-122
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Tidskriftsartikel (refereegranskat)abstract
- In order to determine the total number of fibres and the extent to which the relative occurrence of different fibre types varies within m. vastus lateralis, 15 micrometers thick cross-sections of whole muscles were prepared. The total number of type 1 and type 2 fibres was determined in every 48th square millimetre of the section, and the results thus obtained were analysed using a computer program allowing an assessment of bivariate data in the form of contour plots. The total number of fibres varied both in proximal to distal direction in the same muscle and between individuals. No obvious correlation existed between the mean fibre area and the muscle cross-sectional area. The proportion of type 1 fibres in the whole muscle varied between individuals (from 44% to 57%) with a mean value for all five of 52%. The distribution of different fibre types varied within the muscle, mainly as a function of depth, with a predominance to type 2 fibres at the surface and type 1 fibres in deeper regions of the muscle. Thus, the fibre type distribution in m. vastus lateralis is not random. This must be taken into consideration when data on fibre type composition are compared with functional variables
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