4 research outputs found
Paravertebral muscles in experimental scoliosis: a light and electron microscopic study
Experimental! structural dextroconvex scoliosis was produced in rabbits by costotransversolisis with transversectomy and releasing of paravertebral muscles between TVII and TX on the right side. Two compensatory curves developed on the upper dorsal and lumbar levels. Biopsies of paravertebral muscles in experimental animals included, besides areas of normal tissue, a considerable derangement of the cell contractile apparatus with sarcoplasmic dilation and eventual cell disintegration and necrosis. Histological changes varied along levels, the convexit!~ being more affected. The severity of changes and retiuction in body weight and length were correlated with the degree of scoliosis. A selective atrophy of slow-twitch fibers was observed in experimental animals, especially at the level of the main curve, whereas fast-twitch fiber atrophy was more important caudally. Control animal biopsies always appeared normal. Our experimental model shows an overt participation of paravertebral muscles in the establishment of compens,atory processes following scoliosis, although the role that paravertebral muscles play in the etiopathogenesis of human idiopathic scoliosis requires further investigation
Selective calcification of rat brain lesions caused by systemic administration of kainic acid
Dystrophic calcification of previously
damaged areas of nervous tissue occurs in a wide range
of human diseases. The relationship between astroglial
and microglial reactions and deposits of calcium salts
was studied for up to five months in rats with a brain
lesion produced by systemic administration of kainate.
The morphology and atomic composition of the calcium
salt deposits was also studied. Two types of lesions,
sclerotic and liquefactive, were observed. In sclerotic
lesions hyperplasia and hypertrophy of astrocytes
partially substituted for the lost neurons, reaching a
maximum in about twenty-five days after treatment. In
liquefactive lesions, the astrocytic reaction occurred only
around the liquefactive area. Microglial reaction was
similar in both types of lesion and reached its highest
expression in about twenty-five days. Calcium deposits
were observed in the sclerotic but not in the liquefactive
lesions. Clearly distinguishable granules of calcium salts
were observed in sclerotic lesions under scanning
electron microscopy after only five days post-injection.
The size of calcified granules increased with time
reaching 40 µm or more in diameter at five months. The
atomic composition of these deposits, studied by X-ray
microanalysis, showed a time-dependent increase in
calcium concentration. While there was no clear
relationship between astroglial and microglial reactions
and calcium salt deposits, the systemic injection of
kainate produced progressively larger and more
concentrated calcium deposits in sclerotic, but not in
liquefactive lesions
Paravertebral muscles in experimental scoliosis, a light and electron microscopic study
Experimental! structural dextroconvex
scoliosis was produced in rabbits by costotransversolisis
with transversectomy and releasing of paravertebral
muscles between TVII and TX on the right side. Two
compensatory curves developed on the upper dorsal and
lumbar levels. Biopsies of paravertebral muscles in
experimental animals included, besides areas of normal
tissue, a considerable derangement of the cell contractile
apparatus with sarcoplasmic dilation and eventual cell
disintegration and necrosis. Histological changes varied
along levels, the convexit!~ being more affected. The
severity of changes and retiuction in body weight and
length were correlated with the degree of scoliosis. A
selective atrophy of slow-twitch fibers was observed in
experimental animals, especially at the level of the main
curve, whereas fast-twitch fiber atrophy was more
important caudally. Control animal biopsies always
appeared normal. Our experimental model shows an
overt participation of paravertebral muscles in the
establishment of compens,atory processes following
scoliosis, although the role that paravertebral muscles
play in the etiopathogenesis of human idiopathic
scoliosis requires further investigation