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PubMed2005

Formation of cartilage in congenital bicuspid aortic valves of Syrian hamsters (mesocricetus auratus).

The formation, topographical location and calcification of cartilage in congenital bicuspid aortic valves of 235 Syrian hamsters aged 0--173 days were studied by histological, histochemical and immunohistochemical techniques. In all animals the aortic valve was bicuspid; it had two leaflets, ventral and dorsal, each supported by its own aortic sinus. In 141 valves, a more or less developed raphe was located in the ventral sinus. The remaining 94 valves were devoid of any raphe. The first sign of valvular chondrogenesis was the presence of small groups of cells embedded in a type II collagen-positive extracellular matrix. These cellular groups, which appeared as early as 2 days after birth, became converted into hyaline cartilage or fibrocartilage. A considerable proportion (67%) of the valvular cartilages developed within the first 6 weeks of life. The cartilaginous tissue was capable of forming anywhere along the attachments of the valve leaflets to their supporting sinuses. However, statistical analyses substantiated the observation that the bases of the sinuses and raphes were the valvular regions particularly prone to the development of cartilage. At these sites, the cartilage was usually hyaline and often became calcified. The findings were consistent with the assumption that intense mechanical stimulation plays an important role in the formation of the valvular cartilage. Moreover, these findings supplied new evidence that in the cardiac semilunar valves of Syrian hamsters, cartilage formation does not involve the aggregation of large numbers of cells before their differentiation into chondrocytes. The valvular hyaline cartilages appear to act as competent pivots, resisting mechanical tensions generated during the cardiac cycle. Deposition of calcium in the matrix can be regarded as a reinforcement process of the cartilaginous tissue. Finally, it is hypothesized that the formation of cartilage in the aortic valves of hamsters prevents dystrophic calcification of the valve, a pathological change that causes aortic stenosis in man, especially in patients with a bicuspid aortic valve.

Age Factors↗
PubMed1975

The distribution of different molecular species of collagen in fibrous, elastic and hyaline cartilages of the pig.

The distribution of type II collagen, considered to be characteristic of cartilaginous tissues, was determined in various specialized cartilages of the mature pig. The tissues examined were: (1) fibrocartilage of the semilunar meniscus of the knee; (2) elastic cartilage of the external ear; (3) hyaline cartilage of (a) the synovial joint (b) the thyroid plate of the larynx, and (c) the nasal septum. The predominant species of collagen in each tissue, whether type I or type II, was appraised semi-quantitatively by analysis of purified collagen solubilized by pepsin and of peptide fragments produced by cyanogen bromide. Cyanogen bromide-derived peptides were characterized by column chromatography on CM-cellulose and by electrophoresis in sodium dodecyl sulphate-polyacrylamide gels. The proportion of each type of collagen was determined precisely by isolating the homologous small peptides alpha1(II)CB6 [nomenclature of Miller (1973) Clin. Orthop. 92, 260-280], by column chromatography on phosphocellulose and determining their relative proportions by amino acid analysis. Thus collagen of the fibrocartilage of the meniscus proved to be all type I; type II was not detected. In contrast, collagen of elastic cartilage of the outer ear, after rigorous exclusion of perichondrium, was type II. Similarly, type II was the only collagen detected in all the mature hyalline cartilages examined.

Amino Acids↗
PubMed1998

Functional anatomy of the cartilage of the distal phalanx and digital cushion in the equine foot and a hemodynamic flow hypothesis of energy dissipation.

OBJECTIVES: To examine macro- and microscopic characteristics of cartilage of the distal phalanx (ungual cartilage [UC]) and digital cushion in the equine foot and to relate them to the foot's function of energy dissipation. ANIMALS: 85 horses and 5 foals of various breeds and ages. PROCEDURE: Feet, obtained at necropsy, were perfused with India ink (n = 30), latex (5), or polymer plastic (10). Select feet were examined histologically for tissue architecture and to identify elastic fibers. Immunochemistry to identify substance P peptides in nerves (feet from foals) and gold chloride impregnation of axons (n = 10) were performed. Feet were sectioned transversely (n = 27) or coronally (62 feet in a matched-paired study). Ungual cartilage was measured at the navicular bone. Digital cushions were examined for relative tissue composition between forefeet and hind feet. RESULTS: Ungual cartilage formed an axial projection that extended towards the midline to overlie the bars, and dorsally along the semilunar line of the distal phalanx. Ungual cartilage of forefeet was significantly larger than that of hind feet. The digital cushion was composed of fat and elastic tissues in feet with thin UC, or fibrous and fibrocartilaginous tissue and elastic tissue in feet with thicker UC. Sensory nerves and an extensive network of venovenous anastomoses were found in the UC. CONCLUSIONS AND CLINICAL RELEVANCE: Ungual cartilage and the digital cushion provide the basis for a hemodynamic flow hypothesis of energy dissipation. Maximum energy dissipation depends on proper hoof preparation and shoeing.

Aging↗
PubMed2003

[The injection of acrylic bone cement prevents bone collapse in the intercalar bones lacking bony support: an experimental sheep semilunar bone model].

OBJECTIVES: In a sheep semilunar bone model, we investigated whether collapse in the intercalar bones lacking bony support could be prevented by the injection of acrylic bone cement. METHODS: The study included 16 limbs of eight sheep. Preoperatively, anteroposterior and lateral views of the carpal joints in the fore limbs were obtained. The animals were divided into four groups. In group 1 (n=3) no surgical procedure was performed in the right semilunar bones, whereas the periosteum on the contralateral side was elevated (group 2; n=3). The first two groups were left as controls. In Group 3 (n=5) the left semilunar bones were filled with acrylic bone cement following decancellation of the bone, while the right semilunar bones were left decancellated (group 4; n=5). The sheep were monitored for three months. Radiographs of the carpal joints were obtained to evaluate collapse occurrence in the semilunar bones. Thereafter, the animals were sacrificed and the semilunar bones were excised for biomechanical and histological examinations. Osteonecrosis and cartilage damage were sought and resistance to compressive forces was investigated. RESULTS: Radiologically, the extent of collapse was statistically significant in the semilunar bones in group 4 (p<0.05). The use of acrylic bone cement was found to prevent collapse in group 3, with no significant difference being noted between preoperative and postoperative semilunar bone heights (p>0.05). Biomechanically, the least resistance to compressive forces was measured in group 4 (p<0.05). Histologically, cartilage damage and osteonecrosis were only seen in group 4. CONCLUSION: Our data suggest that the use of acrylic bone cement prevents collapse in the semilunar bones, without inducing any cartilage damage or osteonecrosis.

Animals↗
PubMed1982

[The distribution of cartilage thickness in the distal part of the elbow joint and its functional significance].

The cartilage thickness of the proximal articular surfaces of radius and ulna was examined in 10 human elbow joints, and its distribution was analysed from the functional point of view. The thickness of the cartilage covering of the caput radii increases towards its margin, the greatest thickness beeing found in the ventro-ulnar part. The semilunar notch of the ulna showed the thickest covering in the volar portion on the radial side, likewise the olecranon was relative thickly covered with cartilage. Intermediate there was a zone either with an extremely thin or lacking cartilage covering. After the representation of the individual subjects the average distribution of cartilage thickness was computed. The result was discussed according to Pauwels calculations of the functional stress of the elbow joint. It was proved that, basing on the theory of the causal histogenesis of the supporting and connective tissues there was an in general good conformity. The cartilage free groove is explained by the conception of the loss of congruity due to functional cartilage swelling.

Aged↗
PubMedDate not supplied

[Magnetic resonance of the elbow: technique optimization and definitions of normal anatomical features and their variations].

INTRODUCTION: MRI is a very accurate technique to study the elbow joint, tendon, ligament and chondral structures. In the last years elbow disorders were described by several MR investigators, while we studied MR capabilities in depicting normal elbow anatomy. This investigation might permit the correct differentiation of normal from abnormal MR patterns. MATERIAL AND METHODS: Eleven healthy volunteers (6 men and 5 women, mean age: 27.5 years) were examined. All studies were performed on a 1.5 T imager (Magnetom SP 4000) with two types of receiver: the knee coil was used in 7 volunteers examined in the prone position, with the arm above their head, the elbow extended and the forearm supine and the shoulder coil was used in 4 volunteers examined in the prone position, with the arm above their head, the elbow flexed and the forearm prone. We acquired T1-weighted SE sequences (TR/TE = 690/15 ms, FA 90 degrees, MA 256 x 512, NEX 2,20 3-mm sections with .3-mm interslice gap, FOV 20-22 cm) on the axial, coronal and sagittal planes and T2-weighted GE sequences (TR/TE = 450/10 ms, MA 256 x 256, 3 NEX, 18 4-mm sections with .4-mm interslice gap, FOV 13-18 cm) on the coronal plane. Two MR-expert radiologists studied the images and identified the main anatomical structures of the elbow and 12 smaller reference elements (2 anatomical variants, 4 ligaments, 3 nerves and 3 arteries) describing their MR appearance and pointing out the most effective planes for their representation. Finally, the image quality of the knee coil was compared with that of the shoulder coil. RESULTS: All bones were clearly depicted on the coronal and axial planes, while the semilunar groove and its anatomical variants were best seen on the sagittal plane. The joint cartilage was best depicted on the coronal plane with T2-weighted GE sequences. Collateral ligaments were best seen with the elbow extended and the forearm supine (knee coil), on coronal T1-weighted SE images, where the radial and ulnar collateral ligaments were visible in 71.4% and 85.7% of the subjects, respectively. Annular ligaments, muscles and tendons were best demonstrated on the axial plane with the elbow extended and the forearm supine (knee coil), while the triceps tendon was best recognized on the sagittal plane with the elbow flexed and the forearm prone (shoulder coil). Vessels and nerves were also best seen on the axial plane with the elbow extended and the forearm supine; in particular, the median nerve was visible in 71.4% of the subjects. DISCUSSION AND CONCLUSION: MRI is very effective in representing elbow anatomical structures. Its accuracy depends on elbow (flexed or extended) and forearm (prone or supine) position. The coronal images with the elbow extended and the forearm supine (knee coil) are the most effective to show the ligaments and the joint surfaces between the radial head and the coronoid process of ulna with the capitellum and trochlea of distal humerus, while the axial images best depicted the muscles, vessels and nerves. The coronal and axial planes, with the elbow flexed and the forearm prone (shoulder coil) are poorly effective for anatomical detailing, even though this position is more comfortable for the patient, while the sagittal plane is best suited to depict the triceps tendon. This position may be used when the elbow cannot be fully extended or when the triceps tendon is studied.

Adult↗
PubMed2003

Formation of cartilage in the heart of the Spanish terrapin, Mauremys leprosa (Reptilia, Chelonia).

Cartilaginous deposits are regularly present in the heart of several reptilian, avian, and mammalian species. The formation of these extraskeletal cartilages has been studied in birds and mammals, but not in reptiles. The aim here was to elucidate this question in the Spanish terrapin. Hearts from 23 embryos belonging to Yntema (1968) developmental stages 17 to 26 and eight terrapins age 3 months to 10 years were examined using histological, histochemical, and immunohistochemical techniques. In the heart of the Spanish terrapin (Mauremys leprosa), chondrogenesis can start during embryonic life. Cartilaginous tissue develops from a mesenchymal cellular condensation that extends along the aorticopulmonary septum and the incipient pars fibrosa of the ventricular horizontal septum. This cellular condensation, which is smooth muscle alpha-actin (SMalpha-actin)-negative and type II collagen-negative during stages 17 to 22, acts as a prechondrogenic condensation. In stage 23, production of type II collagen begins in the central core of the condensation and gradually spreads toward its periphery. The type II collagen-positive (chondrogenic) cellular condensation remains devoid of perichondrium prior to birth. Thereafter, it converts into hyaline cartilage that extends along the proximal part of the aorticopulmonary septum and the pars fibrosa of the horizontal septum. Our findings are consistent with the assumption that, as in birds and mammals, the precursors of the cardiac chondrocytes in chelonians are neural crest-derived cells of nonmuscular nature. In addition, they point to the possibility that cells from the neural crest populate the embryonic pars fibrosa of the horizontal septum, thereby contributing to its alignment with the aorticopulmonary septum. In the present species, a second cartilaginous deposit of a hyaline nature extends along the sinus wall of the right semilunar valve of the right aorta, penetrating the fibrous cushion that constitutes the proximal support of the corresponding valve leaflet. This cartilage develops after birth, between the third and eighteenth month of life; its morphogenetic origin is unclear. The cartilaginous foci occurring in hearts of Spanish terrapin appear to act as pivots resisting mechanical tensions generated during the cardiac cycle. In the specimens examined there was no sign of replacement of the cardiac cartilages by bone tissue.

Aging↗
PubMed1977

Meniscal regeneration and postmeniscectomy degenerative joint disease.

The failure of meniscal regeneration via a fibrous semilunar mold can be correlated with an increased incidence of degenerative joint disease. Experiments on rabbits revealed a statistically significant relationship between the failure of meniscal regeneration and the development of degenerative joint disease, characterized by osteophyte formation, cartilage pitting and erosions, and loss of carbilage proteoglycan. Similar results in limited studies utilizing adult fox hounds supported this observation. In dogs, variation in the extent of tissues resected about the meniscus, including synovectomy, did not inhibit the reformation of a fibrous semilunar mold. No specific "zone of regeneration" responsible for meniscal regeneration was identified.

Animals↗
PubMed1998

Axial alignment of the lower limb in patients with isolated meniscal tear.

Meniscal tears do not always result from trauma. To elucidate other factors responsible for meniscal tears, we evaluated the axial alignment of the lower limb in 385 patients (385 menisci) with isolated meniscal tear who were examined between 1972 and 1994. The patients were aged 50 years or less and had no ulceration or defect of articular cartilage of the knee when examined arthroscopically. Of the 385 menisci, 90 were lateral complete discoid; 110, lateral incomplete discoid; 68, lateral semilunar; and 117, medial semilunar. Patients in each of these four groups were divided into four subgroups according to sex and whether there was an obvious history of trauma. The so-called Mikulicz's mechanical axis of the affected side was utilized to evaluate the alignment. The axial alignment of the lower limb was normal in the patients with isolated tears of lateral complete discoid meniscus, lateral incomplete discoid, or lateral semilunar. It appeared that the axial alignment of the lower limb did not have a relationship with the occurrence of these tears. Patients with isolated tears of medial semilunar meniscus without obvious trauma, showed varus deformity of the knee. This deformity appeared to be closely related to the presence of medial meniscal tear.

Adolescent↗
PubMed1990

Congenital rudimentary medial meniscus--report of a case of development arrest of medial meniscus.

We present an unusual case, where the medial meniscus does not coincide with the embryological development of the formation of a discoid cartilage. A fairly, careful perusal of English literature since 1945 to date makes us feel that the following case merits recording. The meniscus had a normal anterior horn attached to the intercondylar area, in front of the anterior cruciate ligament. Medially, it was attached to the capsule and the condylar surface of the medial tibial plateau. The posterior horn was rounded, smooth, and floating free of any attachments. It was approximately 2 cms in length, semilunar in shape, and extended posteriorly up to the anterior margin of the medial collateral ligament. The rest of the medial tibial plateau had no other protective covering.

Adult↗
PubMed1988

Early alteration of synovial membrane in osteoarthrosis.

Biopsy specimens of the synovial membrane were obtained during arthroscopy and surgical meniscectomy from the knees of 20 patients with meniscus lesions. The aim of this study was to identify the morphological and immunological changes which appear in the synovium during the earliest phase of osteoarthrosis. Interstitial deposits of IgG and, in some cases, C3 were found not only in patients with evident arthrotic degeneration (cartilaginous lesions and synovitis), but also in patients who showed no overt arthrotic changes. Furthermore, light and electron microscopy showed an increased number of mast-cells with peculiar semilunar or piecemeal aspects of their secretory granules. These ultrastructural modifications are characteristic of slow, chronic release of mediators in response to a constant, moderate degranulatory stimulus. Our findings suggest that synovial changes may occur before the advent of cartilage degeneration and that the latter may be directly influenced by early pathological changes in the synovial membrane.

Adolescent↗
PubMed1986

Isolation and characterization of high-buoyant-density proteoglycans from semilunar menisci.

Proteoglycans were extracted from adult canine menisci in high yield and were purified, and the major species were characterized biochemically. Most proteoglycans in menisci were isolated in the high-buoyant-density fraction. By agarose-acrylamide composite gel electrophoresis, two proteoglycans were seen in this fraction. Although they were smaller than those from porcine laryngeal hyaline cartilage and had shorter chondroitin sulphate and keratan sulphate chains and a lower carbohydrate-to-protein ratio, they were functionally similar to those in hyaline cartilage in their specific interaction with hyaluronate.

Animals↗