Studies on rickets

Sheldon, H.; Robinson, R. A.

doi:10.1007/bf00339514

Cited by 20 publications

(3 citation statements)

References 53 publications

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“…A characteristic result of this imbalance is enlargement of the cartilaginous growth plate (Park, 1939;Simmons & Kunin, 1970). The extractable lathyritic collagen samples of rachitic and non-rachitic growth plates were found to be similar in a-chain distribution and amino acid composition, being of the type [al (11)13, consistent with histological studies in which the rachitic growth plate had been shown to be cartilaginous (Park, 1939;Sheldon & Robinson, 1961). Whether the observed difference in the glutamate content (Table 1) is due to the possible presence of a contaminant or reflects a true primary structural difference cannot be distinguished at present.…”

Section: Discussionmentioning

confidence: 52%

“…A second major feature of rickets is the accumulation of osteoid at the endochondral, periosteal and endosteal sites of ossification (Park, 1939;Engfeld & Zetterstrom, 1955;Sheldon & Robinson, 1961;Baylink et al, 1970). It has been shown that a process of 'maturation' of osteoid to bone matrix occurs before calcification (Baylink et al, 1970), but it is not known whether 'maturation' involves an alteration in the existing osteoid matrix or its complete replacement by that of bone.…”

Section: Discussionmentioning

confidence: 99%

“…Although the collagens of cartilage and bone are different from each other in primary structure, nothing is known about the detailed composition and structure of osteoid. In growing animals made rachitic by vitamin D deficiency, the cartilaginous growth plate ossifies at a retarded rate and is greatly enlarged, and osteoid accumulates along the newly forming bony trabeculae at the endochondral, endosteal and periosteal sites of ossification (Park, 1939;Engfeld & Zetterstrom, 1955;Sheldon & Robinson, 1961;Baylink et al, 1970;Simmons & Kunin, 1970) (see also Plate 1).…”

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Collagen heterogeneity within different growth regions of long bones of rachitic and nonrachitic chicks

Toole

Kang

Trelstad

et al. 1972

Biochemical Journal

112

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The different anatomical regions involved in osteogenesis in the chick long bone have been examined for heterogeneities in collagen structure that might relate to the mechanism of ossification. Experimentally induced lathyrism was employed to enhance collagen solubility, and vitamin D deficiency to allow accumulation of osteoid, the precursor of bone matrix. The extractable lathyritic collagens of the cartilaginous and osseous regions of growing long bones from rachitic and non-rachitic chicks were examined for alpha-chain type and amino acid composition. In both groups of animals the growth plate and cartilaginous regions of the epiphysis gave collagen molecules of the constitution [alpha1(II)](3), whereas the ossifying regions contained [alpha1(I)](2) alpha2. The degree of hydroxylation of the lysine moieties was increased by approximately 50% in the alpha1(I)-chain and alpha2-chain of rachitic bone collagen. Since uncalcified osteoid is greatly enriched in rachitic bone, it is concluded that the collagen of osteoid has the configuration [alpha1(I)](2) alpha2, similar to that of bone matrix, but has an elevated hydroxylysine content. The possible relationship of this difference to the mechanism of calcification is discussed.

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Section: Discussionmentioning

confidence: 52%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Collagen heterogeneity within different growth regions of long bones of rachitic and nonrachitic chicks

Toole

Kang

Trelstad

et al. 1972

Biochemical Journal

112

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An electron microscopic investigation of osteogenesis in the embryonic chick

Decker

1966

Am. J. Anat.

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Cell-matrix and bone-matrix relationships have been studied by electron microscopy in the diaphysis of chick embryo tibio-tarsus. Osteoblasts within the periosteum possess cytoplasmic machinery characteristic of cells involved in protein synthesis. They contain abundant ergastoplasm, and an extensive Golgi apparatus. Small vesicles are associated with the juxtanuclear Golgi apparatus as well as with the extensive ergastoplasm. This suggests that the mechanism of protein synthesis and its transfer to the external milieu may be similar to that of other protein secreting cells, the fibroblast, the odontoblast and the chondroblast.A rather wide variation in collagen fibril diameter is seen in those fibrils located between the osteoblasts and the initial ossification area. The first nucleation of apatite crystals is seen as random aggregations distinct and separate from the collagen fibrils. This appearance is independent of section orientation since there appeared to be no difference between sections oriented at right angles to or parallel with the diaphysis' long axis.The observations of this study are consistent with proposed mechanisms for the nucleation phenomenon involving the ground substance and collagen fibrils. In addition, the observations suggest a concept of cellular control over the extracellular environment effecting the initial crystal nucleation. The morphologic evidence indicates that the molecular arrangement of collagen as fibrils probably does not provide the mechanism for apatite crystal nucleation.The process by which apatite crystals are incorporated into the matrix of bone remains obscure despite the efforts of many investigators in a number of disciplines over the past few years.There is definite controversy concerning the relative roles that collagen, the extracellular milieu, and the osteoblast play in the initial deposition or nucleation of the apatite crystals.Recently Glimcher ('59) has focused attention on the role collagen plays in the nucleation phenomenon in vitro and in vivo. His electron micrographs present evidence that the apatite crystals reinforce the native collagen periodicity and align themselves preferentially along the longitudinal axis of the collagen. His conclusion was that collagen acts as a "catalytic heterogeneity for the nucleation of apatite crystals."Cameron ('63) in a recent review article has rejected this hypothesis based on his observations in the rat of a "random distribution of the patches of calcification and the absence of nuclei at regular sites in relation to bands on the collagen fibrils.''

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Vascular invasion of the epithyseal growth plate: Analysis of metaphyseal capillary ultrastructure and growth dynamics

Hunter

1990

Anat. Rec.

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Metaphyseal blood vessels which invade the calcifying epiphyseal growth plate were examined by a variety of techniques to determine their morphology, cell division, and growth patterns as they relate to endochondral ossification. Four regions of these vessels were characterized: 1) sprout tips--the terminal ends of the capillary sprouts which impinge upon the hypertrophic chondrocytes of the growth plate; 2) region of extended calcified cartilage--those deeper vessels within the metaphysis which are surrounded by an extracellular matrix predominantly composed of extended septa of calcified cartilage; 3) region of bone deposition--further still from the epiphysis these microvessels are contained within a network of active bone deposition laid upon a scaffold of calcified cartilage; 4) region of primary vessels--at a distance of 350-500 microns from the epiphysis are dilated vessels with one or two layers of smooth muscle in their walls, which supply and drain the metaphyseal capillary plexus. The sprout tips are continuous blind-ended vessels lined with an attenuated endothelium with no underlying basement membrane. Dividing endothelial cells are most frequently found in the region of bone deposition 175-200 microns behind the apices of the growing sprout tips. A time-coursed, autoradiographic examination of cytokinesis revealed radio-labelled endothelial cells to appear at the epiphysis after a 24 hr period. The metaphyseal capillary sprouts represent a continuous, unidirectional angiogenic vascular network which grows by elongation from the region of bone deposition; this region remains a fixed distance behind the sprout tips. These findings are discussed in light of the growth dynamics between this vascular plexus and the epiphyseal growth plate.

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Studies on rickets

Cited by 20 publications

References 53 publications

Collagen heterogeneity within different growth regions of long bones of rachitic and nonrachitic chicks

Collagen heterogeneity within different growth regions of long bones of rachitic and nonrachitic chicks

An electron microscopic investigation of osteogenesis in the embryonic chick

Vascular invasion of the epithyseal growth plate: Analysis of metaphyseal capillary ultrastructure and growth dynamics

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