. Compendium of histology. Histology. 88 EIGHTH LECTURE. In small embryos one obtains thin (0x045 to mm.), but long ( to mm.) spindle cells, with one or two vesicular nuclei, and in the centre commencing for- mations of transverse lines, that is with a transformation into sarcous elements. With an increase in nuclei, the structure increases not only in length but also in breadth. The transverse striation advances towards the ends, but leaves the axial portion still free. We still meet here with the old protoplasm. Later, however, after the longitudinal markings have also appear
. Compendium of histology. Histology. 88 EIGHTH LECTURE. In small embryos one obtains thin (0x045 to mm.), but long ( to mm.) spindle cells, with one or two vesicular nuclei, and in the centre commencing for- mations of transverse lines, that is with a transformation into sarcous elements. With an increase in nuclei, the structure increases not only in length but also in breadth. The transverse striation advances towards the ends, but leaves the axial portion still free. We still meet here with the old protoplasm. Later, however, after the longitudinal markings have also appeared, this protoplasma has disappeared, with the exception of a slight residue, which surrounds the nucleus and thus forms the muscle corpuscle. We find the latter, at last, in mammalia and man, displaced towards the periphery. We have already above (p. 82), declared the sarcolemma of the transversely striated filament to be a homogeneous boundary layer furnished by the adjacent connective tissue. All investigators do not, however, coincide with our view. The muscular filaments of the new born are still much finer than those of the adult. The subsequent increase in thick- ness explains in great part the growth of the muscle in transverse diameter. New fibres are also subsequently developed (Budge). This has, it is true, been recently disputed. Weismann observed that the muscles of the frog divide in a longitudinal direction, with a prodigious increase in their nuclei. One then sees regular columns of nuclei de- scending near each other. The filament di- vides, one becomes two, which subsequently acquire the normal diameter by a growth in thickness. The two products of division may afterwards repeat the same cleaving pro- cess. A single muscular filament may in this way finally become a whole group of filaments. Among the forms of retrogression of our tissue, fatty degeneration is the most frequent (Fig. 85).. Fig. 85.—Fatty degen- erated human muscular fibre ; a, slighter ; /;,
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