Distribution Of Glycosaminoglycans Research Articles

Distribution of extracellular matrix components in nuchal skin from fetuses carrying trisomy 18 and trisomy 21

We have investigated histologically the elevations of the skin in dorsal and lateral neck (nuchal) regions of human fetuses carrying karyotypes of trisomy 18 (Edwards' syndrome) and trisomy 21 (Down's syndrome). Cavities filled with interstitial fluid were found in the dermis, epidermal basement membrane and occasionally in the epidermis of trisomy-18 fetuses, but were not delineated by an epithelium or basement membrane as judged by the absence of immunostaining for laminin, collagen IV and collagen VII. Dilated vessels were also found at the interface between dermis and subcutis. Neither normal fetal skin nor that of trisomy-21 fetuses contained cavities or dilated vessels. In order to detect possible alterations of the extracellular matrix in trisomy-18 and trisomy-21 skin, the distribution of glycoproteins, glycosaminoglycans and proteoglycans was studied immunohistochemically. In trisomy-21 and control skin, the dermis stained intensely for fibronectin, whereas the subcutis reacted only weakly. In trisomy-18 skin, the stronger staining for fibronectin appeared in the subcutis, and the prevailing collagen type was collagen III, collagen type I being absent. In the skin of trisomy-21 fetuses, collagen VI was more irregularly arranged and densely packed, whereas collagen I was more widely spaced than in normal fetuses. More hyaluronan was present in the dermis and subcutis of trisomy-21 fetuses than in that of trisomy-18 and control fetuses. A correlation seems to exist between undelimited cavities and collagen III in trisomy-18 skin, and between hyaluronan and the specific arrangement of collagen in trisomy-21 skin.

Histochemical characterization of the interphotoreceptor matrix in the retina of Octopus bimaculoides

Proteoglycans, located in the interphotoreceptor matrix (IPM) of vertebrate retinas, mediate interactions between the photoreceptors and retinal pigment epithelium. Molluscan retinas also have an IPM located between apposing rhabdomeres. Like the cone matrix sheath of the vertebrate IPM, the octopus IPM is labeled by peanut agglutinin (PNA) and contains retinoid-binding-like proteins. In this study we demonstrate further similarities of the vertebrate/invertebrate IPM and identify specific molecular components in this extracellular compartment of the octopus retina. For light microscopy, paraffin-embedded sections of octopus retinas were stained with dyes specific for acid mucopolysacharides including Alcian blue and colloidal iron. In addition, sections were digested with enzymes specific for hyaluronan, chondroitin sulfate, and sialoglycoconjugates. Digestion of sections with these enzymes and subsequent staining with Alcian blue or colloidal iron demonstrated the presence of chondroitin sulfate and sialoglycoconjugates in the octopus IPM as well as other retinal layers and cells. At the electron-microscope level we treated retinal tissue with Cuprolinic Blue and observed the distribution of sulfated glycosaminoglycans along the rhabdomere edges facing the IPM and in a more central area of the IPM where microvillous processes of supportive cells are located. The octopus IPM may have importance in retinal structure and may be a scaffolding on which molecular components of the IPM are located.

Joint resurfacing using allograft chondrocytes and synthetic biodegradable polymer scaffolds.

Cartilage implants which could potentially be used to resurface damaged joints were created using rabbit articular chondrocytes and synthetic, biodegradable polymer scaffolds. Cells were serially passaged and then cultured in vitro on fibrous polyglycolic acid (PGA) scaffolds. Cell-PGA constructs were implanted in vivo as allografts to repair 3-mm diameter, full thickness defects in the knee joints of adult rabbits, and cartilage repair was assessed histologically over 6 months. In vitro, chondrocytes proliferated on PGA and regenerated cartilaginous matrix. Collagen and glycosaminoglycan (GAG) represented 20 to 8% of the implant dry weight (dw), respectively, at the time of in vivo implantation; the remainder was PGA and unspecified components. Implants based on passaged chondrocytes had 1.7-times as much GAG and 2.6-times as much collagen as those based on primary chondrocytes. In vivo, cartilaginous repair tissue was observed after implantation of PGA both with and without cultured chondrocytes. Six month repair was qualitatively better for cell-PGA allografts than for PGA alone, with respect to: 1) surface smoothness, 2) columnar alignment of chondrocytes, 3) spatially uniform GAG distribution, 4) reconstitution of the subchondral plate, and 5) bonding of the repair tissue to the underlying bone. These pilot studies demonstrate that it is feasible to use cell-polymer allografts for joint resurfacing in vivo.

Organ glycosaminoglycan distribution after intravenous and oral administration in rats.

Organ glycosaminoglycan distribution after intravenous and oral administration in rats.

Core protein structure and sequence determine the site and presence of heparan sulfate and chondroitin sulfate on syndecan-1.

Most proteoglycans bear either chondroitin sulfate or heparan sulfate chains linked to serine residues at Ser-Gly attachment sites on the core protein. However, only a fraction of proteins with Ser-Gly sites exhibit glycosaminoglycan chains. A variable proportion of these sites may be glycanated, and an unknown mechanism distinguishes whether these sites are for chondroitin sulfate or heparan sulfate. To evaluate the core protein features that determine whether and where chondroitin sulfate or heparan sulfate will be linked, we have studied mouse syndecan-1, a transmembrane proteoglycan that is invariably glycanated and can contain both chondroitin sulfate and heparan sulfate chains. The extracellular domain of the syndecan-1 core protein contains five Ser-Gly sites, three clustered near its N terminus and two adjacent to the transmembrane domain near its C terminus. We have established the distribution of glycosaminoglycans on these attachment clusters. In contrast to the C-terminal cluster, the N-terminal cluster was always glycanated, suggesting that this domain of the core protein contains sequences responsible for the invariable attachment of glycosaminoglycan chains. Solely chondroitin sulfate was found on the C-terminal cluster. This cluster contains the sequences EGSGE and ETSGE, both estimated to be on the protein surface in a hydrophilic environment. Heparan sulfate was found solely on the N-terminal cluster, which also bears some chondroitin sulfate. This cluster contains the sequences FSGSGTG and DGSGD, the former estimated to be in a hydrophobic pocket and the latter, similar to the sequence on the C-terminal cluster, in an exposed hydrophilic region. This glycosaminoglycan distribution was identical on mouse syndecan-1 produced by either mouse epithelial (NMuMG) or hamster mesenchymal (CHO) cells, suggesting that site-specific attachment of glycosaminoglycans is independent of cell type. These results implicate a cellular mechanism that distinguishes among the potential sites and attaches the correct glycosaminoglycan type unambiguously. Thus, structural elements of the core protein other than the Ser-Gly attachment sites determine if a site will be glycanated and, if so, whether with chondroitin sulfate or heparan sulfate.

Articular cartilage thickness and glycosaminoglycan distribution in the young canine knee joint after remobilization of the immobilized limb

The recovery of articular cartilage from atrophy induced by joint immobilization was investigated in immature dogs. In a previous study, we showed that 11 weeks of immobilization of the knee (stifle) joint of young dogs reduced the concentration of articular cartilage glycosaminoglycans (GAGs) by 13-47%. In the present study, right hindlimbs from six female beagles were immobilized for 11 weeks, as in the previous study, and then were remobilized for 15 weeks. Cartilage from the knee joint was compared with cartilage from nonimmobilized knees of eight age-matched control beagles. Histological samples taken from 11 different locations of the knee joint were stained with safranin O, and microspectrophotometry was used to demonstrate distribution of GAGs in the tissue. After remobilization, GAG concentration was restored in the patellofemoral region and tibial condyles. On the summits of the femoral condyles, and especially at the periphery of the femoral condyles, GAG concentration remained 8-26% less than the control values. On the summits, the thickness of the uncalcified cartilage was as much as 15% less than in the age-matched controls. Consequently, the changes induced by unloading were reversible to a great extent, but a full restoration of articular cartilage was not obtained at all sites of the knee joint within the 15 weeks of remobilization. Immobilization of the skeletally immature joint therefore may affect the development of articular cartilage in such a way that very slow recovery or permanent alterations are induced.

Glycosaminoglycan Distribution in Chondro-Osteogenesis Induced by Bone Morphogenetic Protein in Mouse Muscle Tissue with the Use of Monoclonal Antibodies.

Glycosaminoglycan Distribution in Chondro-Osteogenesis Induced by Bone Morphogenetic Protein in Mouse Muscle Tissue with the Use of Monoclonal Antibodies.

Immunohistochemical localization of glycosaminoglycans in experimental rat glioma models

Changes of glycosaminoglycan distribution in and around C6 glioma and ethylnitrosourea(ENU)-induced glioma in rats were investigated using monoclonal antibodies that specifically recognize epitopes on chondroitin-0-sulfate proteoglycan (C-0-S), chondroitin-4-sulfate proteoglycan (C-4-S), dermatan sulfate proteoglycan (DS), chondroitin-6-sulfate proteoglycan (C-6-S) and keratan sulfate proteoglycan (KS) after chondroitinase ABC digestion. In the normal brain tissues, C-0-S was located on the surface of the neurons. In addition, extracellular staining in the cerebral cortex and axoplasmic staining in the brain stem and the reticular thalamic nucleus were seen. C-0-S was negative, however, both in the C6 and ENU-induced gliomas. C-4-S or DS was detected only in some of the neurons in the normal brain tissues. They were detected in the peripheral part of the ENU-induced gliomas, but not in the C6 gliomas. C-6-S was located on the surface of some neurons and in the white matter of the normal brain, but it was not detected in C6 gliomas. In all ENU-induced gliomas, C-6-S was identified in the adventitia of the vascular structures within the tumor. In some of them, C-6-S appeared in the peripheral part of the tumor. KS was immunostained in the glial cells in the hippocampus, corpus callosum, brain stem, and the floor of the third ventricle. It was also detected in the peritumoral brain tissues both in the C6 and ENU-induced rat gliomas. The significance of glycosaminoglycans in these glioma models was discussed.

In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondrial defect model

Summary The uptake and distribution of intramuscularly (IM) administered tritium-labeled polysulfated glycosaminoglycan ( 3 H-PSGAG) in serum, synovial fluid, and articular cartilage of eight horses was quantitated, and hyaluronic acid (HA) concentration of the middle carpal joint was evaluated in a pharmacokinetic study. A full-thickness articular cartilage defect, created on the distal articular surface of the left radial carpal bone of each horse served as an osteochondral defect model. 3 H-PSGAG (500 mg) was injected IM, between 14 and 35 days after creation of the defects. Scintillation analysis of serum and synovial fluid, collected from both middle carpal joints at specific predetermined times up to 96 hours post-injection, revealed mean 3 H-PSGAG concentrations peaked at 2 hours post-injection. 3 H-PSGAG was detected in cartilage and subchondral bone 96 hours post-injection in samples from all eight horses. There were no statistically significant differences in 3 H-PSGAG concentration of synovial fluid or cartilage between cartilage defect and control (right middle carpal) joints. HA assay of synovial fluid revealed concentrations significantly increased at 24, 48, and 96 hours post-injection in both joints. The concentration nearly doubled 48 hours post-injection. However, no statistically significant differences were found between synovial concentrations of HA in cartilage defect and control joints. 3 H-PSGAG administered IM to horses, was distributed in the blood, synovial fluid, and articular cartilage. HA concentrations in synovial fluid increased after IM administration of polysulfated glycosaminoglycan.

Determination of the average molecular size of glycosaminoglycans by fast protein liquid chromatography

The determination of the molecular masses of glycosaminoglycans (GAGs) has in the past been hampered by a lack of readily available standards. In the present study methods were determined for the fractionation of commercially available bovine tracheal chondroitin sulphate A into essentially mono-disperse GAG pools which were shown to be suitable as standards for the calibration of Superose 6 and 12 fast protein liquid chromatograph (FPLC) columns. Superose 6 FPLC was particularly suitable for assessing the size distribution of GAGs of M r 10 000–40 000 and the relatively high flow-rates possible with this support enabled a considerably faster analysis of samples compared to the soft gels previously used for this purpose.

Neonatal Porcine Endometrial Development Involves Coordinated Changes in DNA Synthesis, Glycosaminoglycan Distribution, and 3H-Glucosamine Labeling1

To determine whether neonatal porcine endometrial development involved alterations in endometrial DNA synthesis, glycosaminoglycan (GAG) distribution, and/or 3H-glucosamine labeling, gilts were assigned randomly at birth (Day 0) to be hysterectomized on either Day 0, 7, 14, 28, 42, or 56. Uteri were processed for histology and Alcian blue-8GX (AB) histochemistry or cultured as explants in the presence of [methyl-3H]thymidine (3H-Thd) or D-[6-3H]glucosamine (3H-GlcN) and processed for subsequent autoradiography. For 3H-Thd-labeled tissues, labeling index (LI; % of nuclei labeled) was determined for two endometrial tissues (epithelium and stroma); two epithelial areas (luminal and glandular); and, for glandular epithelium, in three endometrial zones (zone 1 = shallow, zone 2 = intermediate, zone 3 = deep). For 3H-GlcN-labeled tissues, LI (grains/100 microns2) was determined for two stromal zones (shallow and deep). Endometrial glands were absent on Day 0, present in shallow stroma on Days 7 and 14, and extended to the myometrium in tissues from Day 28 through Day 56. Appearance of endometrial glands was associated with a dramatic increase in glandular epithelial 3H-Thd LI, which was maximal on Days 7 and 14 and declined thereafter. When glands were present in all three endometrial zones (Days 28-56), glandular epithelial 3H-Thd LI was consistently greatest in zone 2. Stromal 3H-Thd LI decreased after Day 0. In tissues obtained after Day 0, a distinct zone of alcianophilia was observed in shallow stroma adjacent to luminal epithelium and surrounding the necks of newly developed endometrial glands. This staining pattern was marked in tissues from Days 7, 14, and 28. Generally, stromal 3H-GlcN LI was greater in shallow than in deep stromal zones; it decreased after Day 0 to minimum values on Days 28 and 42 in both zones, and increased slightly in shallow stroma on Day 56. Data indicate that development of the neonatal porcine endometrium between birth and Day 56 involves coordinated alterations in patterns of DNA synthesis, GAG distribution, and glycoconjugate biosynthesis. The morphogenetic processes characterized here are likely to be regulated locally via changes in tissue microenvironment.

Distribution of glycosaminoglycans in the intima of human aortas: changes in atherosclerosis and diabetes mellitus

Arterial glycosaminoglycans are considered to be important in atherogenesis due to their ability to trap lipid inside the vessel wall and to influence cellular migration and proliferation. Atherosclerotic lesions have displayed an altered glycosaminoglycan content and distribution. Diabetes is a recognized risk factor for atherosclerosis, but no information is available on the arterial glycosaminoglycans in human diabetes. We examined glycosaminoglycans in normal and atherosclerotic intima of non-diabetic and Type 2 (non-insulin-dependent) diabetic patients. Intima was stripped from autopsy samples of thoracic aortas; normal and plaque areas were separated. Glycosaminoglycans were isolated by delipidation, proteolytic digestion, and precipitation and characterized by quantitation of total glycosaminoglycan and evaluation of glycosaminoglycan distribution by electrophoresis and densitometry. Results indicate a significant decrease in total glycosaminoglycan and significant changes in their distribution in atherosclerotic plaques: a relative decrease in heparan sulphate, a relative increase in dermatan sulphate and thus a decrease in the ratio of heparan sulphate to dermatan sulphate. A similar but less marked change in the ratio was found in normal intima of diabetic subjects, while in their plaques this change was more pronounced. This suggests that changes in arterial glycosaminoglycans (especially the ratio of heparan sulphate to dermatan sulphate) precede the development of lesions in diabetes and may be important in atherogenesis.

Disruption of sulphated glycosaminoglycans in intestinal inflammation

We have studied the distribution and nature of sulphated glycosaminoglycans (GAGs) within normal and inflamed intestine. There is increasing evidence that these negatively charged polysaccharides, which both regulate the ability of albumin to leave the vasculature and inhibit thrombosis, may be affected by inflammatory cells and their products. We obtained samples of freshly resected intestinal tissue from eight controls, eleven patients with Crohn's disease, and six with ulcerative colitis. Sulphated GAGs were detected by means of a gold-conjugated poly-L-lysine probe, and the tissue density of anionic sites was assessed semiquantitatively by means of a Lennox graticule. In normal intestine there was staining in the vascular endothelium and the subepithelial basal lamina and throughout the extracellular matrix of the lamina propria and submucosa. Tissue from the patients with inflammatory bowel disease showed inflammation macroscopically and on histology. There were profound abnormalities of extracellular matrix GAGs, limited to the mucosa in ulcerative colitis and greatest in the submucosa in Crohn's disease. There was also substantial loss of GAGs from the subepithelial basal lamina in both disorders and from the vascular endothelium in submucosa in Crohn's disease. The extent of local GAG disruption was associated with the distribution of macrophages immunoreactive for tumour necrosis factor α and the activation marker RM 3/1. We suggest that inflammatory disruption of vascular and connective tissue GAGs may be an important pathogenetic mechanism, contributing to the leakage of protein and fluid, thrombosis, and tissue remodelling seen in inflammatory bowel disease.

Age-related changes in glycosaminoglycan distribution in different anatomical sites on the surface of knee-joint articular cartilage in young rabbits

In spite of the fact that the various anatomical regions of a given articular cartilage surface are subjected to different degrees of stress, the present observations strongly suggest that there exists a topographical homogeneity in the distribution of glycosaminoglycans in the same articular cartilage. In contrast to this age-related changes in the proportion of the different types of glycosaminoglycan species in articular cartilage are remarkable. Non-sulphated chondroitin could only be detected in very young articular cartilage. Dermatan sulphate, which has already been detected in young adult rabbits, was followed by the appearance of keratan sulphate in older rabbits. Chondroitin 4-6-sulphates were detected in all articular cartilages studied, the proportion of the 6-sulphated variably increasing with age. The present report suggests that the distribution of glycosaminoglycans in articular cartilage varies with species and age, and the data can further vary, depending on the methods used. It is therefore concluded that generalizations against the results reported in the literature should be considered skeptically.

The glycosaminoglycans in cultures of stimulated rat peritoneal macrophages. 2. Gel chromatographic studies and the behaviour of heparan sulfate.

The molecular weight distribution of pMP-derived glycosaminoglycans (GAG), i.e. non-sulfated GAG, chondroitin sulfate (CS), and heparin sulfate (HS)-like material was determined. The peritoneal macrophages (pMP) were harvested from rats normal or stimulated by i.p. injection of thioglycolate, carrageenan or BCG, and maintained in culture. The GAG of cell layer and medium were isolated separately after labeling with 35S-sulfate and 3H-acetate. Treatment with nitrous acid served to remove HS-like material. Labeling with 3H-acetate served to detect synthesis of the high m. w. hyaluronic acid (HA). Gel chromatic separation was done using Sephadex G-200 columns. The maximal size of 35S-labeled GAG, especially HS (36 kDa), was reduced in cultural medium and cell layer after stimulation in vivo. Reduction was most pronounced after application of carrageenan followed by thioglycolate and BCG/LPS stimulation. The extracellular GAG of BCG-stimulated pMP were smallest, probably due to degradation. Heparan sulfate-like material made up a larger proportion in monolayer and medium, comprising the total m.w. range up to 36 kDa. The GAG sensitive to nitrous acid were maximal in cultures of carrageenan-stimulated pMP and minimal in those of thioglycolate-stimulated pMP. This type of HS was sensitive to hyaluronidase, too. Any synthesis of high molecular hyaluronic acid was not found in normal or stimulated rat pMP. Therefore MP-associated HA must be adsorbed from other sources or synthesized by early forms of macrophages.

1110 Distribution of proteoglycan and glycosaminoglycans in the olfactory epithelium and nerve in chick embryos

1110 Distribution of proteoglycan and glycosaminoglycans in the olfactory epithelium and nerve in chick embryos

Histochemical and immunohistochemical distribution of glycosaminoglycans, type II collagen, and fibronectin in developing fetal cartilage of congenital osteochondrodysplasia rat (ocd/ocd).

The osteochondrodysplasia rat (ocd/ocd) is a lethal dwarfism. The ocd/ocd shows histological abnormalities of the epiphysis, characterized by a decrease in amount of glycosaminoglycans (GAGs) in the extracellular matrix (ECM). The present study describes histochemical and immunohistochemical distributions of GAGs, type II collagen, and fibronectin (FN) in abnormal humeral cartilage of the ocd/ocd fetuses on days 16-21 of gestation. A wide-spread region with severe necrosis was observed in the cartilage on days 20 and 21. The affected cartilage has small amounts of ECM, irregular columnizations, thinner hypertrophic zones, and expanded and pyknotic chondrocytes on days 16-21 of gestation. The severely expanded chondrocytes did not have cytoplasmic glycogens on days 19-21. Reactions for chondroitin sulfate (CS) and hyaluronic acid (HA) in the ECM were consistently lower in ocd/ocd than in +/+ during the entire period of observation, although there were granules immunoreactive to CS within the chondrocytes of ocd/ocd. The distribution of type II collagen seemed normal in relatively normal regions in the affected cartilage. Strong reactions for CS, HA, type II collagen, and FN were present in the necrotic region on days 20 and 21 of gestation. These findings suggest that the affected chondrocyte may have some defects in releasing ECM substances, which may be released by the process of cell rupture. We hypothesize that some defects in releasing processes inherent to the ocd/ocd cartilage may relate to cellular differentiation and cell death.

Immunoelectron microscopic studies of glycosaminoglycans in the metaphyseal bone trabeculae of growing rats.

The types and distribution of glycosaminoglycans (GAGs) were studied immunocytochemically in osteoid, mineralized bone matrix, and cartilage matrix of growing rat metaphyseal bone after aldehyde fixation and EDTA demineralization, using four monoclonal antibodies (mAbs 1-B-5, 2-B-6, 3-B-3 and 5-D-4). These mAbs specifically recognize epitopes in non-sulphated chondroitin (C0-S); chondroitin 4-sulphate (C4-S) and dermatan sulphate (DS); chondroitin 6-sulphate (C6-S) and C0-S; and keratan sulphate (KS) respectively. In osteoid, all mAbs except 1-B-5 weakly stained matrix material on and between collagen fibrils, and moderately stained organic material corresponding to bone nodules, which are known sites of mineralization. However, the staining of osteoid abruptly decreased at the mineralization front; weak staining was confined mostly to the organic material of bone nodules in mineralized bone matrix, with very weak or no staining of the rest of the bone matrix. This staining progressively decreased toward the mineralized cartilage matrix and became negative. The mineralized cartilage matrix and lamina limitans reacted strongly with all mAbs except 5-D-4. These results indicate that osteoid contains sulphated proteoglycans containing C4-S and/or DS, C6-S and KS, and subsequent bone matrix mineralization appears to require accumulation of these macromolecules within bone nodules and eventual loss of these substances for complete mineralization, whereas proteoglycans containing C0-S, C4-S and/or DS, and C6-S still exist in mineralized cartilage matrix and lamina limitans.

Articular Cartilage Thickness and Glycosaminoglycan Distribution in the Canine Knee Joint After Strenuous Running Exercise

The influences of the strenuous running training program on the knee joint articular cartilage was studied in six female beagle dogs. At the age of 15 weeks, the dogs started running on a treadmill inclined 15 degrees uphill. Thereafter, the dogs were trained for 40 weeks, five times a week. For the final 15 weeks, the dogs ran 20 km/day. Six age-matched female beagles served as controls. The cartilage surfaces were intact after the running exercise. The training reduced the thickness of the uncalcified cartilage by 6% in the medial femoral condyle. The glycosaminoglycan concentration was reduced an average of 11% on the summits of the femoral condyles. The reduction was most pronounced (41%) in the superficial 50-micron cartilage zone. In other regions of the knee, such a decrease of glycosaminoglycans was not observed. A shift to strenuous running voided the increase in cartilage thickness and proteoglycan content previously observed after moderate running. Strenuous running induced marked depletion of proteoglycans from the superficial layer of the femoral condyles at sites subjected to highest impact loads.

The relationship of mechanical properties to morphology in patellar tendon autografts after posterior cruciate ligament replacement in sheep

In a sheep model the posterior cruciate ligament (PCL) was replaced by a patellar tendon autograft (PTAG) using the central one-third of the ipsilateral patellar tendon (PT). The sheep were sacrificed at 16, 26, 52 and 104 weeks postoperation. The PTAG, and, as controls, the contralateral PCL and PT were harvested. These were examined using biomechanical testing as well as light and transmission electron microscopy, including immunohistological techniques. The material properties (maximum stress, elastic modulus) were compared to the morphological features. The cellular distribution, the distribution of glycosaminoglycans (GAGs), the collagen fibril diameter and the occurrence of Type III collagen were studied. Prior to transplantation, the PTAG was shown to be superior in maximum stress (57.2 ± 5.5 MPa vs 41.3 ± 1.9 MPa) and elastic modulus (368.8 ± 49.3 MPa vs 172.3 ± 14.6 MPa) to the PCL. The early decline in material properties of the PTAG (maximum stress 22% and elastic modulus 42% of the control) after free grafting paralleled a cell- and capillary-rich PTAG tissue with remnants of necrosis and a poorly organized extracellular matrix. Two years after implantation, with progressive alignment of the tissue matrix, maximum stress and elastic modulus acquired approximately 60 and 70% of the control, respectively. However, there was also an evidence of degenerative changes characterized by acellular areas, loss of the normal bundling pattern of collagen fibers and abnormal accumulation of GAGs. Ultrastructurally, there was a predominant shift to thin collagen fibrils in the PTAG compared to PCL and PT, both consisting of thick and thin collagen fibrils. Thin fibrils were demonstrated to be, in part, split thick fibrils as well as newly formed fibrils. Most of these thin fibrils revealed a positive reaction with antibodies to Type III collagen.