Ultrastructural study of cutaneous lesions in feline eosinophilic granuloma complex

The purpose of this study was to investigate the ultrastructural appearance of flame figures, reported to comprise a mixture of degenerate collagen and degranulated eosinophils, in feline eosinophilic granuloma complex (EGC). Skin specimens from eight cats with EGC and from two clinically healthy cats were examined by transmission electron microscopy. Flame figures appeared to comprise ultrastructurally normal collagen fibrils separated by oedema and surrounded by large numbers of degranulating eosinophils. Longitudinal sections of collagen fibrils displayed the characteristic cross-striation of normal dermal collagen. Feline eosinophils, analogous to human eosinophils, degranulated both by cytolysis and piecemeal degranulation. The results of this study suggest that flame figures form in feline EGC due to eosinophil recruitment and degranulation, and that collagen fibres are partially disrupted but collagen fibrils are not damaged. These findings suggest that eosinophil accumulation and the release of granule contents represent the primary events in feline EGC.     

牛旋毛虫病肌组织病理形态学及包囊形成的观察

用旋毛虫对3头牛成功地进行了实验性人工感染,并用光学显微镜和电子显微镜系统观察了牛肌旋毛虫的形态学变化、肌组织的病理变化及旋毛虫包囊的形成。经口感染旋毛虫后第7d,牛肌组织中出现旋毛虫幼虫,呈杆状,位于肌纤维之间。感染后11d,幼虫进入肌纤维之中,呈杆状。感染后19d,幼虫的一端出现弯曲,并开始包囊的形成,感染后27d,幼虫蟠曲,100d以后,形成完整包囊,其形状为梭形或卵圆形。电镜下观察,包囊壁分为内、外两层,外层由胶原微纤维组成,来自增生的内芽肿;内层由不定形基质、不能显示周期性横纹的胶原微纤维和小泡组成,来自受侵肌纤维。     

Control of the collagen fibril diameter in the equine superficial digital flexor tendon in horses by decorin

The distribution pattern of collagen fibril diameter in the equine superficial digital flexor tendon (SDFT) is known to differ in central and peripheral areas of some regions. This study reports the essence of collagen fibril differences among different regions of the equine SDFT by transmission electron microscopic (TEM) and high-voltage electron microscopic observations and biochemical analysis. The distribution of large collagen fibrils increased but the density of collagen fibrils decreased from the proximal metacarpal region to the distal metacarpal region. Large collagen fibrils with an irregular cross-sectional profile were found more frequently in the middle metacarpal region than in other regions. Three-dimensional reconstruction of images of irregularly shaped collagen fibrils revealed that these fibrils are formed through fusion of small collagen fibrils with large ones. The amount of decorin, which reportedly inhibits the lateral fusion of collagen fibrils, decreased in the direction of the distal metacarpal region. On the other hand, the size of decorin gradually increased in the direction of the distal metacarpal region. These results suggest that regional differences in collagen fibril distribution and density of collagen fibrils in the SDFT are due, at least in part, to fusion of collagen fibrils and the concomitant regional differences in the amount and size of decorin.     

Collagen biochemistry of avian bone: comparison of bone type and skeletal site.

1. Skeletal disorders in poultry are of considerable welfare and economic importance. The collagenous matrix in bone is involved in many human skeletal disorders, however little is known about the nature of the collagenous matrix in avian bone. 2. This paper describes an investigation of the collagen and mineral biochemistry together with the biomechanics of bone from different sites (humerus and tibiotarsus) and with differing functions (medullary and cortical bone). In vivo and in vitro studies of immature bone assessed the changes in collagen biochemistry during bone maturation. 3. The material strength of the humerus was greater than the tibiotarsus; this difference in strength was reflected in both the collagen and mineral matrix biochemistry. 4. The bone matrix of the humerus was more mature than that of the tibiotarsus, suggesting a higher level of matrix turnover in the tibiotarsus. The pyrrole collagen cross-link concentrations were positively correlated with breaking stress, in contrast to the pyridinoline cross-link concentrations, neither of which showed any correlation with bone strength. 5. The in vivo and in vitro maturation studies underline the importance of the pyrrole cross-link in avian bone and support the mechanism postulated by Kuypers et al. (1992) for the formation of the pyrrole cross-link from a lysine aldehyde and the immature cross-links HLKNL or LKNL. 6. Medullary bone had no biomechanical influence on the breaking stress of the bone. The biochemistry of the matrix was dramatically different. The high level of collagen lysine hydroxylation affected the cross-link profile and may be responsible for the narrow fibrils and disorganised matrix of this bone. 7. Avian bone matrix varies greatly with skeletal site and reflects the differing functions of bone. Further investigation of the collagenous matrix of both normal and diseased avian bone has the potential to aid our understanding of the aetiology of avian skeletal disease.     

Ultrastructure of canine articular cartilage: comparison of normal and degenerative (osteoarthritic) hip joints.

Normal canine hip cartilage was compared with cartilage from the degenerative lesions found in young dogs with canine hip dysplasia. The upper 0.5 mm of normal cartilage was characterized. Four distinct layers or zones were found: a layer of fine fibrous material covering the surface, a layer (surface layer) of small (32 nm diameter or less) collagen fibrils tightly packed in bundles and oriented parallel to the surface, a layer (upper layer) or less tightly packed collagen fibrils oriented mostly parallel to the surface with about 33% of the fibrils 64 nm or more, and a layer (intermediate layer) of randomly oriented fibrils with more than 50% of the fibrils 64 nm or larger. Fibril density was high in the surface layer and decreased with depth into the cartilage. In a moderately advanced lesion of degenerative cartilage, there was a layer of amorphous material over the surface. The tightly packed surface layer of small fibrils was absent. The surface itself was uneven and fissued. At depths from the surface comparable to the upper and the intermediate layers in normal cartilage, the proportion of large fibrils was less than in normal cartilage. The overall density of fibrils in degenerative cartilage increased with depth into the tissue. Cells flattened parallel to the surface, with relatively large nuclei, were found in the upper layer of normal cartilage. Cells in the intermediate layers were larger and round. The oblong cells of the upper layer of normal cartilage were not found in any layer of degenerative cartilage. Differences between cells in other layers of normal and degenerative cartilages were minimal. A model for the arrangement of chondrocytes and collagen fibrils for normal and degenerative cartilage was proposed. Ultrastructural changes in degenerative cartilage were prominent in the upper 0.5 mm of cartilage. These changes were changes in the number of collagen fibrils/mum-2 and a change from a characteristic pattern of collagen fibril diameters and orientation found in normal tissue.     

Growth changes of the collagen content and architecture in the pectoralis and iliotibialis lateralis muscles of cockerels

1. Growth changes of the collagen content and architecture in the pectoralis (PT) and iliotibialis lateralis (ITL) muscles were examined using cockerels from 1 to 14 weeks of age. 2. Total collagen content in PT muscle showed little change, but in ITL muscle reached a maximum at 5 weeks and thereafter decreased slightly until 14 weeks. The collagen content was markedly larger in ITL muscle after 5 weeks. Pyridinoline content of collagen increased abruptly from 5 to 14 weeks in both muscles, but no difference between muscle types was detected. 3. The cell size of the endomysial honeycombs increased with the development of myofibres, and the mesh size of the perimysium around the honeycombs enlarged. 4. In both muscles endomysia were an incomplete network of collagen fibrils with many foramina at one week, became a very thin membrane of felt-like fabric in 2 to 5 weeks and thereafter increased in thickness until 11 to 14 weeks. 5. Perimysial width around the secondary fasciculus differed between the muscle types after 5 weeks. In the wider perimysium of ITL muscle, the collagen fibres increased in number and size to make a stack of collagen bands around the fasciculus. In the narrower perimysium of PT muscle, a few platelets of collagen fibres also developed. 6. The perimysial collagen fibre at 1 to 2 weeks had a smooth surface and appeared to be composed of fine collagen fibrils. The fibre at 11 to 14 weeks showed a rugged surface and was composed of coarser collagen bundles that combined with each other into a net-like configuration with very slim meshes. 7. Our results showed that the collagenous components of chicken intramuscular connective tissue changed markedly during the early period of muscle growth in distribution, architecture and quality but with little difference in quantity.     

A collagen dysplasia in a greyhound bitch

A 10-month-old greyhound bitch was referred to the Massey University Small Animal Clinic in January 1979, with a history of frequently occurring skin lacerations, especially of the feet and limbs. Clinical findings included multiple skin scars, lacerations and hyperextensibility of the skin.

Investigations showed an increased extensibility index of the skin and a sevenfold reduction in its tensile strength, as compared with that of a normal greyhound. On light microscopy dermal collagen fibres appeared to be slightly decreased in density and more whorled in appearance than that of normal sections. Electron microscopy showed dermal collagen fibrils and bundles which were largely normal, but areas could be found, in the papillary layer of the dermis, where malformed fibrils were prominent, and other areas showed disorganisation of fibrillar packing.

These findings indicated that this bitch had features of a collagen fibrillogenesis disorder similar to some of those described in the various forms of Ehlers-Danlos syndrome in man, and cats and mink. Whether the disease is inherited in the greyhound breed has not yet been determined.     

Fine Structure of the Bovine Tapetum Fibrosum

The fine structure of the tapetum lucidum of the domestic cow was studied by electron microscopy. In this ungulate the reflective layer is a tapetum fibrosum situated in the choroid and mainly restricted to the superior fundus. The tapetum is composed of a large array of fine extracellular collagen fibrils separated into lamellae by fibrocytes. The collagen fibrils display the normal cross-striations of native collagen, are 0.2 μm in diameter and are arranged in a hexagonal pattern with a center-to-center spacing of about 0.2 μm. The diameter and spacing of these fibrils is consistent with the constructive interference of reflected light. A vascular lamella adjacent to the retinal epithelial layer contains the choriocapillaris and some irregularly arranged collagen fibrils. The tapetum is pierced by blood vessels which supply the choriocapillaris. Over the tapetum the retinal epithelium is non-pigmented while in nontapetal regions this layer is pigmented. The choriocapillaris is not indented into the retinal epithelium as is the case in species with a tapetum cellulosum.     

Evaluation of Collagen as a Retainer for Autogenous Cancellous Bone Used in Repair of Full Thickness Cortical Bone Defects

A commercially available collagen sponge acting as a cylindrical retainer containing autogenous cancellous bone graft was proposed for treatment of full thickness cortical defects in dogs. Three groups of three dogs each were subjected to removal of at least 1.5 cm of the tibial diaphyses. All tibias were stabilized with bilateral external fixators. Group 1 received collagen surrounding an autogenous cancellous bone graft. Group 2 received collagen and group 3 received no treatment of the ostectomy site. The collagen sponge appeared to allow vascularization of the bone graft as evidenced by new bone formation and was resorbed by 3 months after implantation. Radiographic, histomorphologic, and histomorphometric evaluation at 3 months after surgery showed a greater per cent of bone in the ostectomy site in group 1.     

Comparison of collagen fibre architecture between slow-twitch cranial and fast-twitch caudal parts of broiler M. latissimus dorsi

1. Collagen fibre architectures of perimysium and endomysium in the slow-twitch cranial and fast-twitch caudal parts of broiler M. latissimus dorsi were compared. 2. Type I and III collagens were distributed in both perimysium and endomysium as indicated by their positive immunohistochemical reactions to polyclonal antibodies. 3. Cells invested by endomysium with no myofibres were larger in the cranial part because of the presence of larger slow-twitch myofibres. The honeycomb structure of endomysium was divided into several parts by thick perimysium. 4. The thick perimysial collagen fibres with parallel fibrils, which were interconnected by the loose reticular fibrils and thin fibres, were more numerous and thicker in the cranial part than the caudal. 5. Thick endomysial sidewall of cells in the cranial part was composed of a rougher reticulum of slightly thicker collagen fibrils compared with the thin sidewall in the caudal part. 6. These results indicated that both perimysial constitutions of collagen fibres and endomysial collagen fibrils had attained much larger growth in the slow-twitch cranial part than the fast-twitch caudal in broiler latissimus dorsi muscle.     

Comparative observations of the growth changes of the histochemical properties and collagen architecture of the iliotibialis lateralis muscle from Silky, layer and meat type cockerels

Growth‐related changes in the histochemical property and collagen architecture of the iliotibialis lateralis muscle were compared among Silky, layer and meat cockerels. Histochemical and immunohistochemical methods were employed to observe the collagen architecture. The total intramuscular collagen was also determined. The muscle consisted of type IIA, IIB and IIC myofibers, of which type IIB occurred at the highest frequency. The diameter of type IIB myofibers in each week was largest in the layer, followed by the meat, and was smallest in the Silky. The total amount of collagen reached 3.38 mg/g in the meat bird, 3.03 mg/g in the layer and 2.71 mg/g in the Silky by 30 weeks of age, respectively. In the perimysium, the collagen bundles increased in size and density of fibrils with growth. At 30 weeks of age the layer had compact collagen platelets while the Silky had loose collagen bundles. In the meat bird, the collagen bundles were moderately compact. The endomysial collagen network had a large mesh size at 1 week and thereafter accumulated many collagen fibrils to form a felt‐like fabric of fibrils at 30 weeks of age. From these results it appears that growth‐related changes in the iliotibialis lateralis muscle are not necessarily causally affected by the different growth rates of chicken breeds.     

Histologic and histochemical changes in articular cartilages of immature beagle dogs dosed with difloxacin, a fluoroquinolone

The histologic and histochemical features of quinolone-induced arthropathy were studied using 14 skeletally immature Beagle dogs (3 to 4 months old) dosed orally with difloxacin at 300 mg/kg body weight once daily for 1, 2, 5, or 7 days. A placebo was given to eight other age-matched Beagle dogs that served as controls. A scoring technique that included lesion size and histologic features was used to determine the progression of lesions. Articular-epiphyseal cartilage complexes on the femoral and humeral heads and tibial tarsal bone were identified as predilection sites. Within predilection sites on femoral and humeral heads, lesions developed in specific areas. Lesions appeared within 2 days of the onset of treatment, and lesion scores increased with time. Grossly, the lesions were raised, fluid-filled vesicles on the articular surface. Histologic changes included vesicle formation with loss of proteoglycan, clumping of unmasked collagen, and degeneration and necrosis of chondrocytes. In lesions with higher scores, chondrocytes were often in clusters or they were undergoing metaplasia toward spindle-shaped cells. Although dissolution of matrix and necrosis of chondrocytes were typical of all lesions, smaller lesions had histologically normal chondrocytes adjacent to small vesicles. In sections stained with toluidine blue, proteoglycan was aggregated with collagen fibrils or was absent from the matrix adjacent to vesicles. Unique features, such as biomechanical forces, may predispose specific areas of articular cartilage to develop lesions.     

Effect of skeletal muscle decorin on collagen fibrillogenesis in vitro

The effect of skeletal muscle decorin on collagen fibrillogenesis was investigated, in order to provide background for understanding the functions of decorin in skeletal muscle. The self‐assembly of type I and III collagen with the addition of decorin or the core protein of decorin from bovine neonatal skeletal muscle was monitored using a spectrophotmeter. Time course changes in the absorbance of collagen solutions showed typical sigmoidal curves composed of three phases. The time of the initial phase was not different between the collagen solution with decorin and that without decorin. The increase rate of the absorbance in the second phase decreased with concentration of decorin added in collagen solutions. Similar effects on fibrillogenesis of type I and III collagens were observed when the core protein of decorin was added in collagen solutions. These results suggest that regulation of collagen fibrillogenesis by decorin depends on its core protein. The networks of reconstructed collagen fibrils with decorin were looser than those without decorin. Bovine skeletal muscle decorin could participate in the regulation of collagen fibrillogenesis and in the arrangement of collagen fibrils in the intramuscular connective tissue.     

Effects of inflammatory periodontal disease ('broken mouth') on the ultrastructure of collagen fibrils in the sheep incisor periodontium

The ultrastructure of the matrix of the sheep central incisor periodontium showing clinical signs of severe periodontitis was analysed quantitatively. The distribution of collagen fibril diameters in the lower dental pad changed from a bimodal distribution seen in healthy periodontia to a unimodal distribution. Collagen fibrils with an abnormal morphology were seen in the connective tissue adjacent to the crest of the alveolar bone. These results suggest that the deepening periodontal pocket resulting from inflammation removes the major area of support for the tooth and abnormal loads are applied to fibres deeper within the tissue.     

Comparative observations on the growth changes of the histochemical property and collagen architecture of the Musculus pectoralis from Silky, layer-type and meat-type cockerels

Growth‐related changes in the histochemical properties and collagen architecture of the Musculus pectoralis were compared among Silky, layer‐type and meat‐type cockerels. Histochemical and immunohistochemical methods were used and collagen architecture was studied using scanning electron microscopy. The total amount of collagen present was also measured. The diameter of type IIB myofibers was similar or rather larger in the layer‐type birds compared with the meat‐type. The collagen content was generally low for 5–10 weeks across the breeds and then increased in the other breeds except for Silky. In the perimysium, the collagen bundles gradually increased in size and the density of the fibrils also increased during growth. At 30 weeks of age, the layer‐type birds showed compact collagen bundles while the meat‐type had loose bundles. The endomysial collagen network appeared relatively denser in the meat‐type chicks compared to the others at week 1. At 30 weeks of age, compact and felt‐like structure of endomysium was shown by Silky and layer‐type chickens, while the meat‐type showed a relatively loose arrangement of tissue in the endomysial collagen. From these results, it appears that the meat‐type chicken can produce a large M. pectoralis with many, relatively thinner myofibers and a relatively undeveloped form of intramuscular collagen structure.     

Delayed osteon formation in long-bone diaphysis of an 11-year-old giant cow with dermal dysplasia

The transverse sections of radius diaphysis in an 11-year-old giant Holstein cow with dermal dysplasia of a collagen disorder-related skin fragility (Cow 1), probably based on increasing turnover of the dermal collagen as reported previously, were morphologically and physico-chemically investigated. Cow 1 had about one and a half times as much as the body weight of normal Holstein cows, aged 5 to 6.5 years with stabilized growth. The bone samples were compared with those of a 12-year-old Holstein cow as controls (Cow 2). It has been reported that the long-bone diaphysis of young calves and some herbivorous dinosaurs are occupied with laminar bone showing a concentric appositional formation, and that such a laminar bone is characteristically seen during the growing period of some farm animals and large dogs that show very rapid growth rates. Cow 1 had a smaller number of osteons than Cow 2 in the outer-half layer of the diaphysis, and showed an intermediate type between Cow 2 and a 1-year-old Holstein ox in the entire layers, although their bone volumes were similar among them. There were no significant differences in Ca and P concentrations and the Vickers microhardness values between the bone matrix of Cow 1 and Cow 2. The bone-collagen fibrils of Cow 1 showed uneven diameters and a disordered arrangement. Thus, there may be some relation in collagen formation between the bone matrix of Cow 1 and the dermis. From the remaining volume of laminar bone, Cow 1, aged 11 years, had probably shown growth until quite recently, so that we consider that Cow 1 became a giant animal, in the same way as some herbivorous dinosaurs.     

Abnormalities of collagen fibrils in a rabbit with a connective tissue defect similar to Ehlers-Danlos syndrome

A morphometric ultrastructural study was performed to confirm the presence of an abnormality of the collagen fibrils in a rabbit with a connective tissue defect similar to Ehlers-Danlos syndrome. Median fibril diameter and perimeter were not altered but their ranges were significantly increased. As indicated by the median fibril ‘form factor’, fibrils were significantly more irregular in shape; the range of irregularity in shape was also increased. Fibril periodicity was unchanged. The results are discussed in relation to collagen fibril structure and fibril abnormalities in similar diseases in man and other animals.     

Collagen dysplasia (cutaneous asthenia) in a cat

Hereditary collagen dysplasias comprise a complex group of connective-tissue disorders that result in the reduced tensile strength of affected tissues. These processes are called cutaneous asthenia in the skin of dogs and cats. We report here the case of a crossbred male cat, aged 6 months, that presented with two skin wounds in the region of the right thorax and right iliac tuberosity. The skin of these regions and of the animal's dorsum was hyperextensible, smooth to the touch, and easily torn with minor trauma. Microscopic examination of skin samples revealed reduced dermal connective tissue consisting of shortened and fragmented collagen fibers. Normal fibers were intermingled with altered fibers. Ultrastructural changes in collagen fibers included disorientation of fibrils within the same bundle, marked spacing differences, and variation in the diameter of transverse sections. The fibrils maintained the transverse striations characteristic of normal collagen.     

Histology and ultrastructure of the developing superficial digital flexor tendon in rabbits

This study was designed to investigate the developmental changes in the superficial digital flexor tendon (SDFT) of the white New Zealand rabbit, from 5 to 7 days pre-natal to 112 days post-natal (PN), at histological and ultrastructural levels. The tendons changed from being highly cellular with 13079 ± 2538 cell/mm² and little directional organization to a longitudinally oriented, predominantly connective tissue structure with relatively few, mature tenocytes (2384 ± 365 cell/mm²). Fibrillogenesis was seen in isolated vacuoles of fibroblast cytoplasm during fetal life as well as after birth, but less frequently with increasing age. At the ultrastructural level, there was a progressive increase in the mean diameter of collagen fibrils with age throughout the population , until PN day 28. A bimodal distribution of collagen fibril size was first observed on PN day 56 while at day 112, the fibrils were fully differentiated and showed a multimodal size distribution. The development of elastic fibres preceded that of collagen fibres and accompanied progressively more marked sinusoidal crimping in collagen fibres on PN days 7 and 14. The tendons of older animals became less tightly crimped. The cells of the epi- and endotenon were less mature and relatively undifferentiated compared with the cells in the body of the tendon of the same age, which might explain their ability to initiate healing of tendon injuries in older animals. In conclusion, extensive changes were observed in tendons during growth and maturation, with diameters of collagen fibrils, tissue orientation and cellularity being the parameters affected, probably due largely to increased physical activity.     

Morphological analysis of corneal opacity in Shiba dog with GM1 gangliosidosis

GM1 gangliosidosis is one of the inherited metabolic lysosomal storage disorders characterized by neurological symptoms caused by beta-galactosidase deficiency and consequent accumulation of GM1 ganglioside in neuronal cells. Shiba dogs affected with GM1 gangliosidosis have been found to suffer from corneal opacity. In our morphological analysis, keratocyte enlargement was induced by abnormal intracellular accumulation of neutral carbohydrates, resulting in the loss of normal arrangement of collagen fibrils in the opaque cornea was found to be associated with the disorder. We therefore conclude that corneal opacity in this Shiba dog with GM1 gangliosidosis may be caused by neutral carbohydrate accumulation in lysosomes, swelling and dysfunction of keratocytes, and subsequent irregular arrangement of collagen fibrils in the corneal proper substance.