Connective Tissue Framework Research Articles

The skeletal framework of human kidney and renal cell carcinoma

The three dimensional architecture of the connective tissue framework of normal human kidney and three renal cell carcinomas was studied. A sodium hydroxide maceration technique was used to remove the cellular elements thus exposing the underlying connective tissue structures. The collagen fibrillar network was visualized using the scanning electron microscope. In normal kidney the fibres were fine, and smooth, and corresponded to the shapes of the original parenchymal constituents. The fibres of the kidney tumours were coarse in nature and irregularly distributed. The technique provides a rapid method for studying connective tissue fibres in normal and diseased tissue. The three dimensional architecture thus exposed enhances our knowledge of tumour stroma.

Isotonic muscle and sarcomere shortening in rabbit right ventricular preparations.

Cardiac muscle fibers are suspended within and attached to an elaborate connective tissue matrix that includes numerous compliant interconnections. Myocardial muscle fibers are not branched, but connect at small angles to each other to form a branched array. Therefore, fiber shortening occurs as a vector within a connective tissue framework and individual fiber work may exceed external muscle work. To evaluate the latter we measured isotonic muscle shortening simultaneous with sarcomere shortening. The hearts were obtained from rabbits (n = 4) anesthetized with intravenous pentobarbital sodium. We isolated right ventricular trabeculae or free wall papillary muscles in Krebs-Ringer's solution (2.5 mM Ca2+, 28 degrees C). Cross-sectional area was 0.038 +/- 0.003 mm2 (+/- SE throughout) and resting sarcomere length was 2.33 +/- 0.12 microns. Sarcomere length was measured with laser diffraction (He-Ne, lambda = 632.8 nm) during force clamps in single- and paired-stimulation twitches. Relative sarcomere shortening (delta SL) was isotonic sarcomere shortening divided by sarcomere length at the onset of isotonic shortening. Relative muscle shortening (delta ML) was isotonic muscle shortening divided by muscle length at zero load; the latter was estimated from the stress-strain relation of elastic recoil at the onset of load clamps. Average delta SL/delta ML at peak shortening was 3.38 +/- 0.16 and was independent of stimulus pattern, isotonic load, amount of shortening, time during a twitch or laser beam position along a muscle. Therefore, the ratio greater than 1 was neither a function of activation nor heterogeneous sarcomere length change.(ABSTRACT TRUNCATED AT 250 WORDS)

Scanning electron microscopy of surgically excised human mitral valves in patients over 45 years of age

Leaflets were obtained from 23 diseased mitral valves of patients over 45 years of age removed at the time of prosthetic valve insertion and the topography was studied with scanning electron microscopy. The clinical diagnosis in all cases was probable rheumatic heart disease. Filiform processes (Lambl's excrescences) were seen on 15 of 23 (65%) of these leaflets. Some of these processes appeared to develop when either bundles of collagen or elastic fibers in the connective tissue framework of the cusp were broken. The freed portion of the fiber then served as a nidus for thrombus formation. The endothelium on the surface of the leaflets was consistently altered. Endothelial cells were changed in shape, had microvilli scattered over their exterior, showed discontinuous cell borders and were desquamated, either singly or in groups. Elements of the peripheral blood adhered to the exposed subendothelium. Erythrocytes were usually entrapped in fibrin networks. Single activated platelets and platelet aggregates adhered to the fibers of the exposed subendothelial connective tissue. Surface mineral deposits were composed of granular spherulites, which contained both calcium and phosphorous. This study extends our understanding of the architectural modifications that contribute to the continuing pathologic process of rheumatic mitral valve disease.

Pulmonary lymphatics in SIDS — A comparative morphometric study

Pulmonary lymphatics in a group of SIDS cases were compared with a control group of a similar age distribution. The causes of death in the controls were known to be associated with varying degrees of pulmonary edema. The surface areas of pleural, interstitial, peribronchial, periarterial and perivenous lymphatics were planimetrically measured. The data were statistically tested. The tests showed that the pulmonary lymphatics of the SIDS group were significantly more distended than those of the control group as expressed by highly significant differences in their surface areas. On the whole 2142 lymphatics were measured; 1255 in the SIDS group, which consisted of slides from 10 cases and 887 in the control group which consisted of slides from 11 controls. Although the sample size imposes a limit on the general applicability of the results, the clear distinction between the two groups as shown by the tests do indicate a possible feature of SIDS — lymphatic stasis — which might be secondary to some impairment of lymphatic drainage. This in turn could induce subtle fibrotic changes in the connective tissue framework of these lungs. The results are presented in the light of the forensic significance of the signs of asphyxia frequently found in SIDS and the diagnostic difficulties encountered in differentiating between SIDS and mechanical asphyxia e.g. due to smothering.

Inflammatory pseudotumor of lymph nodes. A distinctive pattern of nodal reaction.

We report seven cases of a previously undescribed, distinctive pattern of nodal reaction resembling inflammatory pseudotumor (IPT) of the lung and other organs. The four men and three women in the series ranged in age from 16 to 62 years (median, 33). All patients presented with prominent lymphadenopathy. Constitutional symptoms were present in five patients, and laboratory abnormalities (especially elevated erythrocyte sedimentation rate, anemia, or hypergammaglobulinemia) in four. All patients recovered (two without treatment) and are alive and well 7-40 months (median, 23) after presentation. Histologically, the process mainly involved the connective tissue framework of the node (hilum, trabeculae, capsule), secondarily spreading into the lymphoid tissue proper and the perinodal soft tissue. It was characterized by a storiform growth pattern, marked vascularity with associated vascular lesions, and a polymorphous reactive cellular infiltrate in a collagen-rich stroma. The differential diagnosis included other reactive processes (Castleman's disease, drug lymphadenopathies), malignant lymphoma (Hodgkin's, peripheral T-cell), histiocytic or reticulum cell lymphomas, and malignant fibrous histiocytoma. Some features of this process appear to be the result of an "acute phase" response; others might be accounted for by a specific target of the initial insult or alterations in the regulation of the inflammatory response to it, rather than by any specific etiologic agent.

Changes in the lung connective tissue framework in sudden infant death (SIDS)

Light microscopy findings are reported on the interstitial connective tissue framework of 45 lungs from babies who died within the first 2 years of life. Thirty were confirmed cases of SIDS and 15 were controls of similar age who died of known causes. The stains applied were H & E, PAS, Prussian blue, Elastica van Gieson, Trichrom (Masson-Goldner), Gomori's silver methenamine and Picro-Sirius polarization (modified). Particular attention was paid to type I and type III collagen, reticulin fibers and ground substance. All investigated cases showed evidence of chronic recurrent interstitial edema in a highly significant frequency and intensity in contrast to the controls. Areas of recent and persistent lymphedema were observed, some of them with reactive fibroplastic activity, which tended towards gradual fibrosis. These changes were irregularly distributed and frequently involved the mural interstitium. Considering the effects of such changes on expansibility, ventilation and perfusion of the lungs, as well as the impairment of gas diffusion, the findings described could be significant in the forensic evaluation of the signs of asphyxia found in most cases of SIDS.

The vascular territories (angiosomes) of the body: experimental study and clinical applications

The blood supply to the skin and underlying tissues was investigated by ink injection studies, dissection, perforator mapping and radiographic analysis of fresh cadavers and isolated limbs. The results were correlated with previous regional studies done in this department. The blood supply is shown to be a continuous three-dimensional network of vessels not only in the skin but in all tissue layers. The anatomical territory of a source artery in the skin and deep tissues was found to correspond in most cases, giving rise to the angiosome concept. Arteries follow closely the connective tissue framework of the body. The primary supply to the skin is by direct cutaneous arteries which vary in calibre, length and density in different regions. This primary supply is reinforced by numerous small indirect vessels, which are “spent” terminal branches of arteries supplying the deep tissues. An average of 374 major perforators was plotted in each subject, revealing that there are still many more potential skin flaps. Our arterial roadmap of the body provides the basis for the logical planning of incisions and flaps. The angiosomes defined the tissues available for composite transfer.

Structural crosslinking of lung connective tissue collagen in the blotchy mouse.

Male mice with the sex-linked mutation Blotchy (Blo) have a defect in copper metabolism which results in deficient activity of a number of copper-containing enzymes. Inbred Blo/y mice spontaneously develop lung abnormalities which resemble emphysema and often die of ruptured aortic aneurysm. Lung, tail tendon, and tibial bone collagens from inbred Blo/y and their normal (+/y) litter mates were reduced with standardized [3H]NaBH4, acid and alkaline hydrolyzed, and chromatographed in order to quantify the aldehydic crosslink precursors, and the labile reducible and nonreducible stable mature covalent intermolecular crosslinks. Reducible lung collagen crosslinks were markedly (60%) decreased in the Blo/y mice and few, if any, mature nonreducible crosslinks were present. Total aldehydes were also decreased (65%) when Blo/y was compared to +/y. In tail tendon and bone, collagen crosslinks were decreased by only 28% and 15%, respectively. Selectively severe lack of activity of the copper-dependent enzyme level oxidase in lung with only partial lack in tendon and bone could account for the results obtained. Alternatively, insufficient reducible crosslinks, coupled with increased collagen turnover in the lung could prevent formation of the more mature stable crosslinks required to provide a proper connective tissue framework for the Blo/y lung.

Uterine growth-promoting effects of relaxin: a morphometric and histological analysis.

The hormone relaxin has been implicated in the regulation of several processes in the reproductive tract during pregnancy and parturition. This study investigated the uterine effects of relaxin in immature and mature ovariectomized, estrogen-primed rats using morphometric and histochemical analysis. Rats were sprayed at 30 or 70 days of age and given estrogen (5 micrograms) 7 days later. After a week, they received an injection of porcine relaxin (100 micrograms) and were killed 6 h later; controls received vehicle alone. Histological sections were obtained from 7 levels of each uterine horn, and the volumes of endometrium and myometrium were calculated by use of a Zeiss Videoplan Computer Image Analyzer. In immature animals, relaxin treatment doubled uterine weights during the treatment period, and cross sections from relaxin-treated animals exhibited significant increases in the areas of both the myometrium and endometrium, 150% and 130% respectively. Mature animals were less responsive to relaxin although they also exhibited significant increases in uterine weight (31%), myometrial volume (29%), and endometrial volume (22%). With the use of Masson's Trichrome stain for collagen, we observed that relaxin alters the connective tissue framework of both endometrium and myometrium; control uterine collagen appears highly organized and dense with compact collagen fibers, whereas the collagen of relaxin-treated uteri is loosely arranged and disorganized with widely separated collagen fibers. Relaxin-stimulated uteri exhibited significantly greater vascularization, as evidenced by the size of arteries and veins in the vascular region between the circular and longitudinal muscle layers. Increased vascularization and uterine blood flow may be one mechanism involved in relaxin's uterotropic effect and is being investigated further.(ABSTRACT TRUNCATED AT 250 WORDS)

Pregnancy-related changes in the connective tissue of the ovine cervix.

During the course of gestation, changes in the metabolism and chemical composition of the cervical connective tissue occur. The concentrations of collagen, proteoglycan and hyaluronate in the cervix decrease with time of pregnancy, while there is a small but significant increase in tissue hydration. The collagen network loses its dense, ordered appearance and assumes a loose, frayed, disoriented structure. A small molecular weight dermatan sulphate proteoglycan with Kav = 0.48 on Sepharose CL-4B has been isolated from pregnant and nonpregnant ovine cervix. Proteoglycans isolated from dilated cervix yield a second peak at the excluded volume of a Sepharose CL-4B column which may represent a new proteoglycan species, or represent a proteoglycan monomer with larger glycosaminoglycan constituents. The rate of synthesis of proteoglycan is enhanced during pregnancy, and doubles in the time between 140 days and term (dilated). The increased rate of proteoglycan synthesis in the presence of a diminishing hexuronate concentration in the pregnant cervix is indicative of enhanced proteoglycan turnover. This may provide some insight into the mechanism whereby a new matrix with altered mechanical properties is produced, since a rapid turnover of matrix components enables a remodeling of the connective tissue framework. This reorganization of the matrix is discussed with respect to parturition.

Alterations in lung basement membrane during fetal growth and type 2 cell development

We studied basement membrane development in the late fetal and in the neonatal rat lung, from the 18th day of gestation (term = 22 days) through the 8th postnatal day, with particular emphasis on the gas-exchange region of the lung. In the periphery of the lung, as type 2 cells differentiate, the continuous basement membrane develops openings beneath these cells. Basal cytoplasmic foot processes extend through these discontinuities into the underlying interstitium, often approaching interstitial cells closely. These discontinuities and extensive foot processes are associated only with type 2 epithelial cells and not with either differentiated airway cells or with the type 1 alveolar lining cells derived from type 2 cells. The type 2 cell basement membrane discontinuities and penetrating foot processes are maximal in the perinatal period and decrease in the week after birth. The appearance of openings in type 2 cell basement membrane and changes in distribution, linear density, and ruthenium red staining of anionic sites suggest that the epithelial basement membrane undergoes continuous remodeling throughout development, particularly in association with type 2 cell differentiation and growth of lung surface area. Epithelial cell foot processes may interact with underlying interstitial cells and affect the coordination of lung surface growth with the development of its connective tissue framework.

Glycosaminoglycans in emphysematous and fibrotic hamster lungs.

Amounts and distributions of glycosaminoglycans were measured in lungs obtained from hamsters treated intratracheally 21 to 30 days previously with either saline, purified pancreatic elastase, or bleomycin. Normal hamster lungs contained 150 to 200 micrograms glycosaminoglycans per lung. Lungs made fibrotic by bleomycin contained significantly more glycosaminoglycans per lung than saline-treated control lungs; this increase was equally distributed among all glycosaminoglycan subtypes. Emphysematous lungs also contained more glycosaminoglycans than saline control lungs; this increase was less than that of fibrotic lungs and was limited to the dermatan sulfate subtype. The latter was increased in emphysematous lungs when expressed as a percentage of total glycosaminoglycans. In these hamster models of lung diseases that affect the connective tissue framework of the lungs, changes in lung glycosaminoglycans accompany changes in the other connective tissue components.

Structural evidence for insertion of collagen fibres to smooth muscle cells in the carotid arterial system of the giraffe (Giraffa camelopardalis).

Previous anatomical studies have failed to resolve the question relating to whether or not collagen fibers, like elastic fibres, are attached to smooth muscle cells in the arterial wall. The current ultrastructural study demonstrates the insertion of collagen fibres to the sarcolemmal dark areas in the smooth muscle cells of the carotid arterial system of the giraffe. It is concluded, therefore, that this morphological linkage between collagen and smooth muscle cells may facilitate transmission of the force of contraction between the cells and to the surrounding connective tissue framework since the myofilaments appear to be spatially placed in series with the extracellular collagen fibres at the sarcolemmal dark areas.

Significance of free-dorsiflexion of the toes in walking.

Dissection reveals that the ball of the foot contains a connective tissue framework with transverse, vertical, and sagittal fibers, all connecting the skin with the proximal phalanges of the toes. Dorsiflexion of the toes tightens the framework and thereby restricts passive movements of the skin, enabling shear forces to be transferred to the skeleton. An electromechanical oscillator was constructed that applied oscillatory shear forces of constant amplitude (+/- 0.2 N) to the skin and at the same time measured the resulting motions. It was found that the toes should be dorsiflexed by 35--40 degrees to restrict skin mobility to 50 per cent and by 50 degrees to restrict it maximally. The results were compared to actual dorsiflexions of toes during walking. These dorsiflexions were measured on slow motion film and with still pictures with light tracks formed by light emitting diodes. Maximal dorsiflexion during push off was found to be 60 degrees for feet walking without shoes, 45--50 degrees for feet walking in soft shoes, and 25--30 degrees for feet walking in a stiff shoe of the minus-heel type. Dorsiflexion was further found significant for arch support and for the mechanics of the forefoot during push-off.

Microstructure of Cuts Through the Connective Tissue Framework of Meal

The connective tissue framework (endomysium and perimysium) of raw meat samples was stained with silver in frozen sections for the light microscope. In bovine sternomandibularis samples which had been slowly and incompletely cut with a sharp blade parallel to the longitudinal axes of the muscle fibers, two major zones of connective tissue deformation were found. In advance of the blade the endomysium was compressed while to the rear of the cutting edge endomysium was stretched. Perimysial septa were pushed into a syncline in advance of the blade and spread tension through the sample by pulling on adjacent endomysium. In samples of porcine longissimus dorsi muscles, the mean numbers of connective tissue boundaries located along pairs of perpendicular transects were correlated with mean muscle fiber cross sectional areas, r=— 0.83, P<0.005. However, endomysial sheaths were often slightly flattened in one direction while perimysial septa were sometimes approximately parallel. In transects through such regions more connective tissue boundaries were crossed in one of a pair of perpendicular transects. Thus, when the meat was transected in only one direction, the correlation between the number of connective tissue boundaries transected and mean muscle fiber cross sectional area was reduced, r=—0.54, P<0.005. This directional effect at the microstructural level was thought to be related to the phenomenon of transverse anisotropy in meat samples during shearing. In bovine sternomandibularis samples cut perpendicularly to the longitudinal axes of muscle fibers, muscles fibers and their endomysial sheaths were compressed in advance of the blade and stretched to the rear of the cutting edge. In samples cut perpendicularly both muscle fibers and endomysial sheaths were severed whereas in samples cut in a parallel manner only connective tissues were severed and most muscle fibers were left intact. In transverse sections of samples from the porcine longissimus dorsi muscle, samples from the anterior half-length of the muscle had more (P<0.01) muscle fibers and endomysial sheaths per unit area than samples from the posterior half-length of the muscle.

Heart volume and myocardial connective tissue during development and regression of thyroxine-induced cardiac hypertrophy in rats.

To determine whether development and regression of cardiac hypertrophy are accompanied by changes in heart volume and to learn whether a change in heart volume is associated with changes in the myocardial connective tissue, cardiac hypertrophy was induced in rats by administration of thyroxine. Rats were given L-thyroxine for 4 weeks. Heart volume was estimated radiologically in vivo at the start of the experiment and at 1- or 2-week intervals for 7 weeks. At each of these stages a number of rats were killed, their hearts were weighed and determinations were made of the myocardial contents of DNA, of collagen measured as hydroxyproline, and of glycosaminoglycans, measured as uronic acid. After thyroxine treatment the ratio of left heart ventricle weight to body weight and of heart volume to body weight rose significantly. The increase in heart weight was greater than the increase in heart volume. At the same time, there was a significant decrease in the concentration of hydroxyproline. After discontinuation of thyroxine treatment heart volume, heart weight and the concentration of myocardial collagen returned to normal within 2 weeks. However, the total amount of myocardial collagen was still less than normal at 2 weeks. The results suggest that the decrease in the amount of myocardial collagen associated with thyroxine-induced cardiac hypertrophy--because it results in a weakening of the supporting properties of the myocardial connective tissue framework--might contribute to a slight increase in in vivo heart volume.

The Pathogenesis of Pulmonary Emphysema (II)

The most important primary cause of generalized pulmonary emphysema is in all probability the loss of mechanical stability of the connective tissue framework in the lung parenchyma. The complexity of the interrelations and interdependencies between the fibres and the ground substance, leads to the mapping out of a more detailed outline of the vulnerable parts in a similar framework. It is concluded that the junctions especially constitute weak spots. Glycosaminoglycans, glycoproteins and proteoglycans particularly hold a key position as cementing substances. The importance of female sex hormones in the metabolism of the ground substance is indicated. A survey is given of the possible threats to a similar system. An attempt is made to disentangle the multitude of possible pathogenetic pathways which lead to emphysematous disintegration. Perspectives of future emphysema research are discussed on the basis of these considerations. Preventive, protective, and reconstructive measures are proposed.

Collagen fibre bundles of the normal marginal gingiva in the marmoset

The architecture of the gingival and interdental ligaments was studied in celloidin-embedded sections of tissue from young adult marmosets. The animals were free of clinical or histologic manifestations of inflammatory gingival disease. The fibre groups classically described were observed. In addition, several groups of fibres which do not fit into the previous classification were present. The semicircular fibres arise from the cementum near the cementum enamel junction, traverse the free marginal, facial and lingual gingiva, and insert into a comparable position on the opposite side of the tooth at a level just apical to the circular fibres. The transgingival fibres arise from the cementum of one tooth and traverse the free marginal gingiva of an adjacent tooth, and the intergingival fibres course in the free marginal gingiva on both the facial and lingual surfaces of the teeth. Since these fibre groups make up the bulk of the connective tissue framework of the marginal gingival tissues, and they arise from the root surfaces or gingiva of adjacent teeth, there is a major interdependence among the various segments of the gingiva.

Morphology and Enzyme Histochemistry in the Liver of Largemouth Bass (Micropterus salmoides)

Livers of 27 bass collected from streams and an impoundment in Kentucky were subjected to light and electron microscopic as well as enzyme histochemical examination. The connective tissue framework of the liver was primarily collagen and reticulum. Elastic lamellae were seen in hepatic arteries. Hepatic parenchyma was arranged in dual-plated muralia. Hepatocytes contained glycogen, endoplasmic reticulum, mitochondria, and a homogeneous nucleus with one prominent nucleolus. Pancreatic acini were observed in walls and perivascular connective tissue of portal veins. No distinct lobular pattern of parenchyma was observed. The enzyme glucose-6-phosphatase was abundant in cytoplasm of hepatocytes usually forming a perinuclear cuff. Alkaline phosphatase was determined in the sinusoidal border of hepatocytes and in walls of central veins. Differentiation of portal veins from central veins was made on the basis of proximity to the hepatic artery and bile duct.

A Theory of the Pathogenesis of Emphysema.

Excerpt The structure of the lungs is maintained by a connective tissue framework of very considerable tensile strength. Metabolic activity in this extracellular fibrous protein network is very slo...