Biomedical subjects

D H Carter

Publications and source records attributed to D H Carter.

26 records · Page 2Linked to original sources

PubMed1994

The fibrous architecture of the rat periodontal ligament in cryosections examined by scanning electron microscopy.

Cryosections through the incisor and molar teeth of the rat mandible were examined, with and without hyaluronidase pretreatment, in the scanning electron microscope. In the fully erupted molar teeth the fibres of the periodontal ligament were organized into bundles which crossed the space from the alveolus to the cementum and inserted into the associated mineralized tissues. In the erupting incisor teeth, three distinct zones were evident. The outer alveolar and cemental zones were composed of coarse fibre bundles which inserted into the adjacent mineralized tissues, while the middle zone was composed of collagenous laminates running along the axis of the tooth. These observations confirm a proposed model for the structure of the erupting periodontal ligament and suggest that the method used will provide further information about the role of the ligament in tooth support and eruption.

Animals↗

PubMed1993

An immunohistochemical study examining the role of collagen type VI in the rodent periodontal ligament.

The distribution of collagen types I and VI has been examined in the periodontal ligaments of rat incisor and molar teeth using cryosections and immunohistochemical staining procedures. The stain for collagen type I was uniform in all the ligaments examined. Uniform staining for collagen type VI was evident only in the ligament of the fully erupted molars, and the stain was absent from the mid-zone of the ligaments of the erupting molars and incisors. The staining pattern of the collagen type VI antibodies is consistent with previous reports which have suggested that the removal of collagen type VI precedes the degradation of major banded collagen fibrils in remodelling connective tissues. The removal of collagen type VI from the mid-zone of the incisor ligament may precede the remodelling events which facilitate tooth eruption.

Animals↗

PubMed1992

Trabecular generation de novo. A morphological and immunohistochemical study of primary ossification in the human femoral anlagen.

An understanding of trabecular formation in early skeletal development may provide insight into the problem of trabecular replacement in the aging skeleton. In an optical and scanning electron microscope study of the processes of de novo trabecular generation, the immunohistochemical distribution of collagen Types I, II and III, together with the matrix organising proteins fibronectin and tenascin, has been examined in the ossifying human femoral anlage. In the region of the developing spongiosa, the primary osseous trabeculae that arose by endochondral ossification were assembled around calcified cartilage remnants, consisting almost entirely of aggregates of mineralised microspheres. These structures were specifically recognised by antibodies raised against collagen Type II and fibronectin. In contrast, the primary osseous trabeculae that arose by subperiosteal intramembranous processes, were assembled around a framework of prominent coarse fibres that were recognised by antibodies raised against collagen Type III and tenascin. Irrespective of their origin, all the new trabeculae were similar in their general staining character for collagen Type I and fibronectin. However, throughout the developmental stages examined here endochondral trabeculae were separated from intramembranous trabeculae by a discrete boundary of compressed cells and mineralised cartilage.

Bone Development↗

PubMed1991

Immunolocalization of collagen types I and III, tenascin, and fibronectin in intramembranous bone.

Structural components of the organic bone matrix were located by immunohistochemical techniques in fresh-frozen sections of normal and dysplastic bone. Fine and coarse birefringent fibers were identified as separate and distinctive features in the extracellular matrix by antibodies raised against human collagen Type III. The glycoprotein tenascin was located on a proportion of the fibers in a characteristic beaded pattern, which was absent in dysplastic bone. The fibers originated in the periosteum or in the fibrous stroma of the marrow cavity and were oriented with regard to both the spatial and the lamellar organization of the bone. The disposition and composition of the fibers suggests that they form a preliminary framework on which intramembranous bone modeling proceeds, and that the specific location of tenascin on the fibers in normal developing membrane bone may be important in determining the alignment of the bone tissue. Epitopes recognized by the collagen Type I and fibronectin antibodies were demonstrated throughout the mineralized matrix, but their incorporation into the collagen "Type III" fibers was evident only outside the mineralized matrix.

Antibodies↗

PubMed1990

Cancellous bone resorption in the proximal ilium of the ovariectomized rat.

Bone histomorphometry was performed on the proximal ilium of mature Sprague-Dawley rats following ovariectomy, and these rats were compared with sham-operated controls. Bone volume per unit tissue volume (BV/TV), osteoid surface, and the depth and extent of eroded cavities were measured in animals killed at intervals after operation. The rate of bone loss and the mean osteoid surface in the proximal ilium of the ovariectomized rats was significantly greater than that of the control rats over a 210-day postoperative period. The eroded surface and mean trabecular thickness in the proximal ilium of the ovariectomized rats were not significantly different from that of the control rats, and therefore failed to explain the difference in the rate of bone loss. The distribution of the depths of trabecular eroded cavities in the ilium of ovariectomized rats was different from that in the control rats. The loss of trabecular bone mass in the proximal ilium of ovariectomized, mature rats appeared due to increased activity of individual osteoclasts, rather than to increased osteoclast numbers and thinning of trabeculae.

Animals↗

PubMed1990

Histopathological and scintigraphic features of condylar hyperplasia.

This investigation was undertaken to correlate the scintigraphic and histological features of condylar hyperplasia to identify consistent diagnostic findings. A series of 34 surgically excised condyles were examined from a 5 year period. Of these, 20 were diagnosed clinically and histologically as condylar hyperplasia. In 18 of these the presentation was one of increasing facial asymmetry. In all 20 cases there was an increased uptake of Technetium 99 as determined by gamma scintigraphy. The thickness of the fibrous articular layer, undifferentiated germinal mesenchyme layer and the hyperplastic cartilage layer were measured using an eyepiece graticule and the presence and frequency of islands of cartilage in the subchondral bone were noted. 7 patients received tetracycline hydrochloride 14 and 4 days pre-operatively in an attempt to quantify the calcification rate. An uninterrupted layer of undifferentiated germinal mesenchyme is a consistent feature of condylar hyperplasia. An increased uptake on scintigraphy is proportionally related to the thickness of the hypertrophic cartilage and not only to the presence but also the frequency of cartilage islands in the subchondral bone.

Adolescent↗

PubMed1989

Histomorphometry of fresh frozen iliac crest bone biopsies.

Although methods are well established for the rapid histological preparation of fresh frozen soft tissues, they remain inadequate for the preservation of hard tissues. A recent technique for sectioning fresh frozen bone, in which sections can be prepared within an hour, has been applied to undecalcified human iliac crest bone biopsies. Quantitative analysis has shown that the static remodeling variables deduced from frozen sections closely resemble those derived from plastic-embedded sections prepared for routine use by established laboratory procedures. It is concluded that the rapid method is reliable for immediate diagnostic and histomorphometric purposes.

Biopsy↗

PubMed1987

Rapid preparation of fresh-frozen undecalcified bone for histological and histochemical analysis.

An increasing need to be able to relate hard tissue morphology to its histochemistry, and the lack of an adequate methodology, prompted this investigation of polyvinylpyrrolidones of varying chain length as supporting films for the cryomicrotomy of fresh undecalcified cortical and trabecular bone. We developed a method that parallels histological procedures but is biochemically inert and functions at -25 degrees C. Using an LKB heavy-duty cryomicrotome, large numbers of serial sections suitable for histochemistry, immunocytochemistry, or rapid histology can be prepared with ease. Sections from mouse skull, ox vertebra, and human iliac crest illustrate the versatility of the method, and have been examined for the preservation of general morphology and of histochemical activity of those enzymes most prominent in remodeling. The procedure does not preclude the subsequent application of standard hard-tissue embedding methods to the remaining material. Comparison with plastic-embedded bone shows not only close similarities in the structural preservation of the frozen tissue, making possible histomorphometry, but also shows some interesting staining differences. These include the absence of differentiation of the calcification front with toluidine blue stain in fresh frozen specimens, and the presence in frozen osteoid tissue of specific methylene blue metachromasia missing from plastic preparations.

Acid Phosphatase↗