The shield of the domestic boar (Sus scrofa L.): its gross anatomy, histology and possible function.
Explore the source record for details and available documents.
Aging↗
Biomedical subjects
C R Howlett
Publications and source records attributed to C R Howlett.
Omental response to long-term implantation of diffusion chambers containing allogeneic and xenogeneic bone marrow.
Diffusion chambers were filled with bone marrow from 2-4 weeks old rabbits and dogs, and implanted into the peritoneal cavity of adult animals for 28-45 days. The diffusion chambers were encapsulated by omentum in both dogs and rabbits, and the character of the omental response was influenced by the chamber contents. Empty chambers were enveloped by omentum composed principally of fibrous-fatty tissues, with a thin fibrous layer adherent to the chamber walls. Chambers containing allogeneic marrow evoked a marked cellular and angiogenic response in the adherent omentum. In rabbits, lymphocytes were the predominant cell type. In dogs, large ecchymotic haemorrhages were found immediately adjacent to the chambers, with aggregations of lymphocytes in the surrounding dense fibrous tissue. Diffusion chambers containing xenogeneic marrow were surrounded by a thick fibrous tissue capsule, without any adhesion of the omental tissues to the chambers. The internal layer of the omental capsule was necrotic and chambers were bathed in serosanguinous fluid. It was concluded that antigens on fragments of marrow cells escaping from the diffusion chambers had evoked the various omental responses which were observed.
Animals↗
An unusual congenital osseous tumour in a foal.
Explore the source record for details and available documents.
Animals↗
Infestation in the dog by the paralysis tick Ixodes holocyclus. 1. Clinical and histological findings.
Under laboratory conditions 8 dogs were infested with Ixodes holocyclus and the clinical signs and histological findings were recorded. Seven of the dogs developed clinical signs of the disease, died and were subjected to a post-mortem examination, while the eighth dog remained normal. The clinical signs were consistent between animals and enabled the course of the disease to be subdivided into 5 stages to facilitate analysis of data in future experiments. The most prominent feature of the disease was dysfunction of the efferent motor system although some disturbance of the afferent pathways and involvement of the autonomic nervous system did occur. The period elapsing between attachment of the ticks and onset of signs varied from 5.5 to 7 days, while the mean duration of the disease was 23.3 h. The histopathology demonstrated moderate to severe congestion of the liver, kidney and lungs, and in some lung sections pulmonary oedema was present.
Animals↗
Skin neoplasms of dogs in Sydney.
In a survey of dogs in Sydney, mastocytomas (16.1%) and histiocytomas (14.0%) were the most common in a total of 1,000 skin neoplasms. The basal cell and appendage group provided 25.5% of the neoplasms. The prevalence of the various neoplasms, the age of affected dogs, the proportion in the sexes, the common sites of occurrence and prevalence in the different breeds were broadly similar to findings in surveys in other countries, except that in the Syndeny dogs there was a greater prevalence of histiocytomas and haemangiopericytomas, a more common occurrence of histiocytomas in mature dogs, an occurrence of histiocytomas in similar numbers on the head, trunk and limbs, and a remarkably common development of squamous cell carcinomas in Dalmatians.
Age Factors↗
Effect of a static magnetic field on fracture healing in a rabbit radius. Preliminary results.
To ascertain what effect a static magnetic force has on a healing fracture, samarium cobalt magnets were implanted adjacent to induced radial fractures in adult rabbits. A magnetic field of 220-260 G was generated at the fracture site. The radii were allowed to heal for four weeks and the contralateral fractured bones acted as controls. Healing bone units were assessed microscopically and mechanically. Significantly greater forces (p less than 0.01) were required to break those bone units exposed to magnetic fields. However, no significant difference was found when comparing the longitudinal midcallus areas from magnetized and nonmagnetized limbs.
Animals↗
Mineralization in in vitro cultures of rabbit marrow stromal cells.
Localized regions of mineralization were found in confluent cultures of rabbit marrow fibroblastic cells. The mineralized tissue developed within clusters of giant fat cells in the spaces between the cells. Investigations with light and electron microscopy demonstrated that in these sites there was some differentiation of the fibroblastic cells in an osteogenic direction, shown by changes to more polygonal shapes, and the synthesis of well-banded collagen similar to that found in bone tissue. Differentiation may be due, in part, to increased cell density in a confined space. Growth of the mineralized tissue was observed in the living cultures with a fluorescence microscope. Electron probe microanalysis confirmed that the mineral formed was hydroxyapatite. Initiating sites of mineralization included membranous vesicular bodies, lipid, and products of cellular degeneration. Once initiated, mineralization appeared to spread rapidly into adjacent collagenous and other structures, suggesting the appearance of a mixture of skeletal-type and dystrophic mineralization.
Animals↗
Anatomic and radiographic appearance of a sesamoid bone in the tendon of origin of the supinator muscle of dogs.
Radiologic and anatomic studies of the elbow of 100 dogs of 17 different breeds showed that a sesamoid bone may be located in a constantly present sesamoid cartilage associated with the tendon of origin of the supinator muscle. The sesamoid was observed in 31% of the radiographs of 100 supinator tendons dissected from 50 of the dogs. The bone was usually bilateral and was best demonstrated in craniocaudal medial-to-lateral oblique radiographs of the elbow where it articulated with the craniolateral aspect of the head of the radius.
Animals↗
The fine structure of the proximal growth plate of the avian tibia: vascular supply.
The vascular supply to the proximal tibial growth plate of the 7 weeks old chicken is described using various vascular markers. In addition the ultrastructure of metaphyseal and epiphyseal vessels as well as their supporting tissue is reported. The metaphyseal arterioles terminate in large calibre vessels which have occasional endothelial gaps and no basement membrane or supporting cells, and therefore could be classified as venous sinusoids. In contrast the epiphyseal arteriole terminates in a capillary-venule plexus lined by an attenuated and fenestrated but continuous endothelium. This paper definitively establishes that communication of epiphyseal and metaphyseal vessels across the avian growth plate does not occur. The eosinophilic streaks which often join these two vascular supplies have been described ultrastructurally and would appear to be remnants of the 'retreating' epiphyseal vessels.
Animals↗
Studies on cell lineage of metaphyseal bone in repleted scorbutic guinea pigs.
Young weanling guinea piglets were placed on a diet deficient only in vitamin C. When they reached a state of severe scorbutus, they were given vitamin C and the morphological differentiation of various mesenchymal cells in the proximal end of the tibia was followed over 7 days. The altering metaphyseal cellular pattern is recorded descriptively as well as quantitatively. Levels of mesenchymal cells, preosteoblasts, osteoblasts, and osteocytes remained relatively steady for 24 h. However, by 48 h there was a precipitous decline of mesenchymal cells with a concomitant rise in recognizable osteogenic cells; this change continued until the 7th day of repletion. At this time, with the exception of the preosteoblasts, the cellular population had returned to about the level in the control animals. Osteoclastic and endothelial cellular movements fluctuated widely during the period of repletion under examination. These results support the concept of separate lines of differentiation for osteoclasts and osteoblasts in the postnatal animal. Moreover, mesenchymal cells appear to be precursors of osteogenic cells.
Animals↗
Characteristics of advanced porous and textured surface pacemaker electrodes.
Reduced stimulation thresholds, improved sensing and better attachment have been claimed for totally porous and porous surfaced electrodes. In this study, the potential for clinical use of two new types of porous electrodes and a non-porous, textured high microsurface area electrode, has been evaluated by comparison with equivalent sized, smooth non-porous controls. Eighteen sintered and seven laser drilled porous electrodes, seven-non-porous textured electrodes, and sixteen controls, were implanted singly in the right ventricles of sheep. Measurements of threshold, pacing, sensing and bulk impedances were taken at regular intervals for up 180 days. At sacrifice, only three of the thirteen non-porous controls were attached. All laser porous electrodes, apart from two which were dislodged, were attached, as were eleven of fifteen sintered porous, and five of seven textured non-porous electrodes. Tissue ingrowth was found for both porous electrode types. Stimulation thresholds were not statistically different for all electrode types (p less than 0.05). Pacing and bulk impedances of the two porous and surface textured electrodes were significantly higher (p less than 0.10, p less than 0.05, respectively) than those of controls. The three new electrodes exhibited similar chronic sensing impedance values, 30% less than equivalent non-porous electrodes. The similar sensing performance of the porous and high microsurface area non-porous electrodes indicates that the nature of the external surface, rather than internal porosity, determines sensing impedance. All three new electrode types showed improved attachment and sensing compared with similar smooth electrodes. The laser porous electrode, which permits fixation by tissue ingrowth and maintains simplicity of construction, is promising for routine clinical use.
Animals↗
The effect of long-term low-dose diphosphonate treatment on rat bone.
Weaning, male rats were given ethane-1-hydroxy 1,1-diphosphonate (EHDP) or dichloromethylene diphosphonate (Cl2MDP) 0.5 mgP/kg/day for 140 days. Samples prepared after sacrifice were: (1) thin ground (30 micrometers) transverse tibial sections, (2) methacrylate-embedded 5 micrometers sections of the proximal tibial metaphysis, and (3) ultrathin calcified metaphyseal sections for electron microscopy. Cl2MDP reduced the diaphyseal medullary cavity, and EHDP increased the osteoid width. Both drugs increased endosteal bone apposition (possible secondarily to the impaired resorption) and, perhaps as a result, periosteal apposition was increased. Consequently, diaphyseal bone area was unchanged. Metaphyseal bone area was increased and osteoclast numbers reduced, in contrast to the increased osteoclast numbers reported previously in animal experiments with diphosphonates. Acid phosphatase activity within osteoclasts was markedly reduced with EDHP and unchanged with Cl2MDP. The ultrastructural changes in osteoclasts, i.e., a deficiency of ruffled borders, reduced numbers of cytoplasmic vacuoles and the presence of crystals between bone and the osteoclastic plasmalemma, were more marked with EHDP than Cl2MDP.
Animals↗
Functional adaptation of bone in response to sinusoidally varying controlled compressive loading of the ovine metacarpus.
To obtain carried load, quantitative data relating functional adaptation of bone to controlled, sinusoidally-varying, compressive loading of constant amplitude was applied to the right metacarpal bones via Steinmann's pins inserted through the metaphyses in 13 sheep. Loading was applied for two 1-hr periods/day at 24 cycle/minute, through-out a test period of 28 days. The amplitude of the applied loading was varied from test to test, giving peak stresses on the mid-diaphyseal cross-section that ranged from 2.2-8.3 N/mm2. In the mid-diaphyseal region, the bone responded by periosteal apposition, with maximum proliferation usually occurring on the medio- and laterovolar borders and relatively little new bone on the dorsal and volar aspects. The cross-sectional areas of new bone was roughly proportional to the applied stress, with a maximum increase of approximately 8% in the most highly stressed bones. There was also evidence that periosteal resorption had occurred, presumably as the first step in the apposition process. A significantly increased level of intracortical activity was found in the right metacarpus as compared with the contralateral bone.
Adaptation, Physiological↗
The incidence and importance of tibial dyschondroplasia to the commercial broiler industry in Australia.
1. To survey the relationship between tibial dyschondroplasia (TD) and the down-grading of broiler carcasses three processing plants representing the major breeding and growing organizations in Australia were visited. 2. The incidence of TD for the three flocks examined varied from 14 to 35%. In the flock with the highest incidence of TD there was a direct relationship between the presence of TD and down-grading of carcasses due to leg abnormalities. 3. A genetic analysis was carried out on one of the parent lines of the breeding group with the highest TD incidence. The genetic correlation between body weight and TD incidence at 7 weeks of age was negative, suggesting that continued selection for increased body weight should lead to a reduced incidence of TD. Since this conflicts with usual expectations, possible reasons, including a within-line genotype by environment interaction, are discussed. 4. Because of the substantial genetic component associated with TD, screening of breeding cockerels for its presence if strongly recommended.
Animals↗
Induction of hypersensitivity reactions to Lactobacillus fermentum and lipoteichoic acid in rabbits. Part II.
Regimens of intravenous injections of saline-washed Lactobacillus fermentum elicited hypersensitivity reactions in rabbits. Pathological investigation revealed evidence consistent with induction of aggregate anaphylaxis, characterised by acute cor pulmonale. Additional evidence of similar tissue injury was observed in livers of rabbits which had received several intravenous injections of L. fermentum. Deposition of immune complexes in kidney glomeruli was demonstrated in only 1 out of 11 animals. Skin testing experiments revealed that lipoteichoic acid was involved in type I and type II antibody-mediated hypersensitive states. The involvement of bacterial cell surface components and extracellular products in such reactions implies a potential role in host tissue injury.
Animals↗
Bone reaction to surgical drilling and pinning.
Explore the source record for details and available documents.
Animals↗
The fine structure of the proximal growth plate and metaphysis of the avian tibia: endochondral osteogenesis.
The ultrastructure of endochondral osteogenesis from the proximal end of tibias of 7 weeks old normal White Leghorn and broiler chickens is described. Little, if any, ultrastructural differences exists between these two strains of birds. In the growth plate, proliferation of chondrocytes and their matriceal production is approximately matched by resorption. Erosion of the metaphyseal aspect of the growth plate is accomplished under two sets of circumstances: firstly, when mineralization of the cartilaginous matrix is so scanty as to be discernible only by electron microscopy, and secondly, when calcification is gross and easily appreciated by light microscopy. The former process appears to be accomplished in the main by perivascular mononuclear cells and the latter, to a great extent, by chondroclasts. It appears that metaphyseal blood vessels expand, by saccular protrusions, into pre-existing spaces or those created by cellular erosion. Cones or plates of calcified cartilage, which extend into the metaphysis, act as a template for initial deposition of bone. Osteoblasts recently surrounded by osteoid have adjacent to their plasmalemma a pericellular sheath which is composed of ill-defined clumps of amorphous material as well as some incompletely aggregated collagenous fibrils. Beyond this sheath collagenous fibrils and fibres, with distinct periodicities (ranging from 57 to 69 nm) are observed. Towards the diaphysis the range of the periodicity of fibres in osteoid narrows to 64-69 nm.
Animals↗
Formation of bone and cartilage by marrow stromal cells in diffusion chambers in vivo.
When freshly isolated rabbit marrow cells were cultured either in vitro or in diffusion chambers in vivo, the hemopoietic cells disappeared and there was a proliferation of the stromal cell population. The colonies formed in vitro were mainly fibroblastic, and this cell type predominated in confluent cultures. Staining for alkaline phosphatase activity and for the Von Kossa reaction was negative in in vitro cultures. However, marrow cell suspensions or fibroblasts harvested from in vitro culture of marrow cells, gave rise to a mixture of bone, cartilage and fibrous tissue in diffusion chambers implanted into the peritoneal cavity. In contrast, only a soft fibrous tissue developed from spleen fibroblasts in diffusion chambers. Differentiation of osteogenic tissue within diffusion chambers fell into two categories: (1) Formation of bone in a fibrous layer surrounding cartilage; (2) intramembranous bone formed directly within fibrous tissue unassociated with cartilage. In both cases alkaline phosphatase activity appeared before the onset of mineralization, and decreased as the first signs of mineral became apparent. The present results suggest that postnatal marrow contains osteogenic precursors with the potential to differentiate via either of the two major paths followed during skeletal development in the embryo. Clonal analysis of the marrow stromal cell population will be required to clarify whether osteo-, chondro-, and fibrogenic cells are the products of one stromal cell line modulated by the microenvironment, or whether there are distinct cell lines for each type.
Alkaline Phosphatase↗