Achondrogenesis type II, abnormalities of extracellular matrix

Immune and lectin histochemical and microchemical methods were employed to study growth cartilage from seven cases of achondrogenesis type II (Langer-Saldino). The normal architecture of the epiphyseal and growth plate cartilage was replaced by a morphologically heterogeneous tissue. Some areas were comprised of vascular canals surrounded by extensive fibrous tissue and enlarged cells that had the appearance and histochemical characteristics of hypertrophic chondrocytes. Other areas contained a mixture of cells ranging from small to the enlarged chondrocytes. The extracellular matrix in the latter areas was more abundant and had characteristics of both precartilage mesenchymal matrix and typical cartilage matrix; it contained types I and II collagen, cartilage proteoglycan, fibronectin, and peanut agglutinin binding glycoconjugate(s). Peptide mapping of cyanogen bromide cartilage collagen peptides revealed the presence of types I and II collagen. These observations could be explained by a defect in the biosynthesis of type II collagen or in chondrocyte differentiation.     

Extracellular Matrix of Small Round cell Tumors of Childhood: An Immunohistochemical Study of 67 Cases

Sixty-seven childhood tumors were studied immunohistochemically for the extracellular matrix elements type IV collagen, laminin, and fibronectin. Tumors included Ewing's sarcoma, primitive neuroectodermal tumor, small cell osteosarcoma, neuroblastoma or ganglioneuroblastoma, rhabdomyosarcoma, and lymphoma. It was found that small cell osteosarcoma was often positive for fibronectin but not type IV collagen or laminin, a new observation. In the lymphomas, matrix proteins were rarely found. Ewing's sarcoma was variably positive for type IV collagen and laminin, but fibronectin was absent. Extracellular laminin and fibronectin were found in one of two cases of primitive neuroectodermal tumor. In neuroblastoma and ganglioneuroblastoma, the matrix components were rarely found. These results, discrepant with findings in cultured cells, may reflect the altered capacity of tumors to produce these proteins in vitro, which suggests that caution should be exercised in drawing conclusions regarding the nature or histogenesis of tumors from data obtained with cultured tumor cells. Embryonal rhabdomyosarcoma frequently contained all matrix elements in the extracellular space and in a dotlike pattern in the cytoplasm; alveolar rhabdomyosarcoma rarely contained these proteins and never exhibited the dotlike pattern. The frequent finding of matrix proteins in embryonal rhabdomyosarcoma but only rarely in alveolar rhabdomyosarcoma and the unique immunostaining pattern in embryonal rhabdomyosarcoma may prove to be a useful adjunct in the diagnosis of childhood tumors.     

Adherence of human newborn infants' monocytes to matrix-bound fibronectin.

The localization of monocytes to sites of inflammation is mediated by interactions with extracellular matrix components including fibronectin, a nonimmune opsonin with binding sites for collagen, fibrin, heparin, and cell surfaces. This study demonstrates that newborn infants' monocytes bind to both gelatin (i.e., denatured collagen) and matrix-bound fibronectin to a degree comparable to that of adult-derived cells.     

High-dose inhaled nitric oxide and hyperoxia increases lung collagen accumulation in piglets

Nitric oxide (NO), a pro-oxidant gas, is used with hyperoxia (O(2)) to treat neonatal pulmonary hypertension and recently bronchopulmonary dysplasia, but great concerns remain regarding NO's potential toxicity. Based on reports that exposure to oxidant gases results in pulmonary extracellular matrix injury associated with elevated lavage fluid levels of extracellular matrix components, we hypothesized that inhaled NO with or without hyperoxia will have the same effect. We measured alveolar septal width, lung collagen content, lavage fluid hydroxyproline, hyaluronan and laminin levels in neonatal piglets after 5 days' exposure to room air (RA), RA + 50 ppm NO (RA + NO), O(2) (FiO(2) > 0.96) or O(2) + NO. Matrix metalloproteinase (MMP) activity and MMP-2 mRNA were also measured. In recovery experiments, we measured lung collagen content in piglets exposed to RA + NO or O(2) + NO and then allowed to recover for 3 days. The results show that lung collagen increased 4-fold in the RA + NO piglets, the O(2) and O(2) + NO groups had only a 2-fold elevation relative to RA controls. Unlike the RA + NO piglets, the O(2) and O(2) + NO groups had more than 20-fold elevation in lung lavage fluid hydroxyproline compared to the RA group. O(2) and O(2) + NO also had increased lung MMP activity, extravascular water, and lavage fluid proteins. MMP-2 mRNA levels were unchanged. After 3 days' recovery in room air, the RA + NO groups' lung collagen had declined from 4-fold to 2-fold above the RA group values. The O(2) + NO group did not decline. Alveolar septal width increased significantly only in the O(2) and O(2) + NO groups. We conclude that 5 days' exposure to NO does not result in pulmonary matrix degradation but instead significantly increases lung collagen content. This effect appears potentially reversible. In contrast, hyperoxia exposure with or without NO results in pulmonary matrix degradation and increased lung collagen content. The observation that NO increased lung collagen content represents a new finding and suggests NO could potentially induce pulmonary fibrosis.     

Skin collagen defects in a patient with juvenile hyaline fibromatosis.

Juvenile hyaline fibromatosis is a rare disorder characterised by multiple subcutaneous tumours, gum hypertrophy, muscle weakness, and flexion contractures of the large joints. Histology shows an abundance of a homogenous, amorphous, acidophilic extracellular matrix in which spindle shaped cells are embedded forming minute streaks. It has been previously suggested that collagen abnormalities may be involved. A 14 month old girl with this syndrome is described in whom postmortem western blot studies were performed. These studies revealed an absent pro-alpha 2(I) chain and an absent collagen type III chain in skin but not in the other organs examined.     

秋水仙碱对成纤维细胞产生细胞因子以及分泌细胞外基质的影响

目的　阐明秋水仙碱对体外培养人肾脏成纤维细胞 (FB)产生炎症因子转化生长因子 β1(TGF β1)、白细胞介素 1β(IL 1β)以及细胞外基质的影响。 方法　体外培养人胚胎肾脏FB ,经不同浓度秋水仙碱 ( 5 0 μmol/L、10 0 μmol/L、2 0 0 μmol/L、4 0 0 μmol/L)预处理 1h后 ,加入含 10 0μg/ml脂多糖 (LPS)的FB完全培养液继续培养 18h ,以未经LPS刺激也无秋水仙碱预处理的FB细胞为对照。实验终点收集细胞和上清。分别利用RT PCR方法观察秋水仙碱对FB产生TGF β1和IL 1βmRNA表达的影响 ;ELISA法测定细胞上清TGF β1、IL 1β以及胶原COLⅢ、COLⅣ蛋白含量。结果　 ( 1)单纯 10 0 μg/mlLPS刺激后 ,FB产生TGF β1和IL 1βmRNA分别较未经刺激的正常对照组上调 3倍 (RI值分别为 6 6 1± 1 6、2 2 3± 2 0 ,q =5 90 5 ,P =0 0 0 2 )和 4 7倍 (RI值分别为2 2 0± 2 2、4 7± 0 8,q =10 6 8,P =0 0 0 9)。细胞上清TGF β1和IL 1β蛋白含量均明显高于基础含量 [TGF β1分别为 :( 5 16± 14 )pg/ml和 ( 4 2 0± 5 ) pg/ml(q =80 3,P =0 0 12 ) ,IL 1β分别为 :( 3 4± 0 3) pg/ml和 ( 0 3± 0 1) pg/ml( q=2 97 9,P =0 0 0 3) ]。 ( 2 )秋水仙碱明显抑制FB之TGF β1mRNA以及蛋白表达 ,而     

Hyperplastic callus formation in osteogenesis imperfecta.

Osteogenesis imperfecta, an inherited disorder of connective tissues, affects roughly (OI) 4000 people in Germany (11). The main clinical symptoms are fragile bones, progressing skeletal deformities, generalized osteoporosis and short stature. Incidentally, the clinical manifestations can range from perinatal lethal forms to phenotypical normal adults. In many instances the underlying causes of the disease are mutations in gene coding for collagen I, the predominant protein in most connective tissues. Fracture healing is usually not impaired, although in a unique group of OI-patients, a tumor-like hyperplastic callus occurs with excessive deposition of extracellular matrix constituents. Biochemical analysis of the callus is reminiscent of bone from early stages of human development and normal fracture healing (e.g. collagen type composition, degree of posttranslational modification). This underlines that, besides collagen mutations, the regulation of collagen synthesis and their posttranslational processing might be disturbed in patients with hyperplastic callus formation.     

Collagen tissue engineering: development of novel biomaterials and applications

Scientific investigations involving collagen have inspired tissue engineering and design of biomaterials since collagen fibrils and their networks primarily regulate and define most tissues. The collagen networks form a highly organized, three-dimensional architecture to entrap other ingredients. Biomaterials are expected to function as cell scaffolds to replace native collagen-based extracellular matrix. The composition and properties of biomaterials used as scaffold for tissue engineering significantly affect the regeneration of neo-tissues and influence the conditions of collagen engineering. The complex scenario of collagen characteristics, types, fibril arrangement, and collagen structure-related functions (in a variety of connective tissues including bone, cartilage, tendon, skin and cornea) are addressed in this review. Discussion will focus on nanofibrillar assemblies and artificial synthetic peptides that mimic either the fibrillar structure or the elemental components of type I collagen as illustrated by their preliminary applications in tissue engineering. Conventional biomaterials used as scaffolds in engineering collagen-containing tissues are also discussed. The design of novel biomaterials and application of conventional biomaterials will facilitate development of additional novel tissue engineering bioproducts by refining the currently available techniques. The field of tissue engineering will ultimately be advanced by increasing control of collagen in native tissue and by continual manipulation of biomaterials.     

Collagen maturation defects in Ehlers-Danlos keratopathy

Ehlers-Danlos syndrome is one of many inherited abnormalities of connective tissue, specifically collagen. A 16-year-old caucasian female with Type VI Ehlers-Danlos syndrome had five unusual corneal findings, four of which have not been reported in association with Ehlers-Danlos syndrome: micro-cornea (previously reported), cornea plana, keratoconus posticus, stromal haze at the level of Bowman's layer and a peripheral ring opacity suggestive of anterior embryotoxon. Type VI Ehlers-Danlos syndrome is associated with deficient activity of lysyl hydroxylase which ultimately is responsible for cross-linking collagen chains, the source of its tensile strength. Genetic regulation of procollagen formation is believed to be mediated by mRNA. Aggregation and maturation in the extracellular matrix is probably influenced and mediated by its evolving biochemical environment, particularly by complex carbohydrate moieties. An understanding of collagen maturation, and the pathophysiologic and biophysical consequences of abnormalities at this level of biochemical organization, permits more specific understanding of ocular dysmorphology and collagen diseases.     

Effect of a synthetic folic acid analogue, 9-methyl-pteroylglutamic acid, on fetal chondrogenesis: ultrastructural observations

Maternally administered folic acid antagonists (x-methyl-PGA and 9-methyl-PGA) are known to produce various skeletal malformations in the neonate. These defects are thought to be due in part to abnormal metabolism and/or deposition of various extracellular matrix components, i.e., collagen and glycosaminoglycans. Experimental reduction of glycosaminoglycan biosynthesis in vitro has been shown previously to alter the spatial orientation and normal pattern of collagen fibrillogenesis. Furthermore, dietary withdrawal of folic acid concomitant with maternal administration of 9-methyl-PGA has been shown to result in abnormal collagen, uronic acid, and hexosamine metabolism by fetal limbs. In the present study pregnant rats were exposed to a transitory folic acid deficiency from day 11 to 14 of gestation and fetal tibias (mid-diaphyseal region) were examined with the electron microscope on day 18 of gestation. Although we were unable to ascertain any aberrant patterns of fibrillogenesis and orientation with respect to collagen, this particular teratogenic regimen resulted in an altered pattern of chondrocyte development when observed at the ultrastructural level.     

胎儿脐静脉脱细胞基质构建组织工程尿道

目的 探讨人脐静脉细胞外基质的制备及其在尿道重建中的应用.方法 采用酶消化、去污剂和渗透溶液方法制备人脐静脉细胞外基质(extracellular matrix,ECM).24只雄性白兔,随机分为A尿道ECM移植组,对照组B、C.A组切除尿道2.0 cm后用人脐静脉ECM修复,术后行组织学、尿流动力学和膀胱尿道造影评价尿道再生情况及功能.结果 经该法处理的人脐静脉细胞全部脱除.A组修复术后2周,脐静脉ECM有单层上皮细胞生长;4周管腔已被上皮细胞完全覆盖;8周可见人脐静脉ECM降解的微小碎片和平滑肌细胞生长,炎性细胞消失;16周尿道大体观、组织学检查均接近C组,平滑肌数量与C组差异无统计学意义(P>0.05),但排列欠规则.膀胱尿道造影无尿液外渗、尿道憩室形成;尿动力学A组与C组膀胱容量、最大尿道压分别与术前比较,差异均无统计学意义(P>0.05),B组无法置入测压管.结论 酶消化、去污剂和渗透溶液法是制备人脐静脉ECM较为理想的方法,人脐静脉ECM可作为尿道重建的良好支架材料.     

Juvenile hyaline fibromatosis in one Turkish child

We describe a case of juvenile hyaline fibromatosis (JHF) in a Turkish child. Only about 40 cases of juvenile hyaline fibromatosis had been reported in English literature as of March 1998, and it had not been reported in English literature from Turkey as of November 1998. Juvenile hyaline fibromatosis characterized by multiple cutaneous masses is a rare hereditary disorder. This disease is usually found in children, and a malfunction of collagen synthesis is considered as the pathogenetic cause. In the presented case, light microscopy demonstrated an abundance of a homogeneous, amorphous, eosinophilic extracellular matrix in which fibroblasts were embedded. Well-formed collagen fibers could not be demonstrated with Gieson's method or with reticulin preparation. The hayalin material periodic acid-Schiff-positive and diastase-resistant, whereas the Congo red method was negative. Immunohistochemically, the spindle-shaped cells were actin (smooth muscle) negative.     

姜黄素抑制脂多糖刺激的系膜细胞增殖及其白细胞介素1β和巨噬细胞趋化蛋白1基因的表达

目的　观察姜黄素对系膜细胞增殖以及对系膜细胞基质蛋白分泌的影响 ,并进一步探索姜黄素对系膜细胞白细胞介素 (IL 1β)和巨噬细胞趋化蛋白 (MCP 1)基因表达的改变。 方法　采用不同浓度姜黄素处理体外培养的人肾小球系膜细胞后 ,分别收集上清液及细胞 ,应用ELISA的方法测定上清液中胶原Ⅳ和Ⅲ的蛋白分泌量 ,MTT法测定系膜细胞活性 (吸光度值 ) ,RT PCR的方法测定系膜细胞IL 1β和MCP 1基因的相对表达量 ,以未加LPS及姜黄素和仅加LPS不加姜黄素作为对照组。结果　当姜黄素浓度大于或等于 6 2 5 μmol/L时 ,系膜细胞增殖明显受到抑制 (P <0 0 1) ,且表现为浓度依赖性。在基础状态下 ,系膜细胞分泌一定量的胶原Ⅳ和Ⅲ [(10± 9 13)ng/ml和 (2 9 5± 0 5 8)ng/ml],亦有MCP 1mRNA表达 [(42 1± 14 98) % ],但IL 1βmRNA几乎不表达 ;经LPS刺激后其胶原Ⅳ和Ⅲ分泌增加 [(138 75± 2 3 2 3)ng/ml和 (38 2 5± 5 38)ng/ml],同时IL 1β和MCP 1基因表达上调 [分别为 (16 91± 1 6 8) %和 (76 6± 6 5 9) % ],而姜黄素浓度为 4 μmol/L时即能明显抑制LPS刺激的系膜细胞胶原Ⅳ和Ⅲ的蛋白分泌 (P <0 0 5 ) ,且在高浓度时作用更为明显 ;同时姜黄素还能消除LPS上调系膜细胞IL 1β和MCP 1基因表达的作用 (P <     

气道平滑肌细胞在哮喘气道重塑中的作用

气道重塑是气道慢性炎症的结果,包括气道壁增厚和基质沉积、胶原沉积、上皮下纤维化、平滑肌增生和肥大、肌成纤维细胞增殖及黏液腺、杯状细胞化生及增生、上皮下网状层增厚、微血管生成等病理改变.在这些病理变化中,气道平滑肌的改变被认为是导致气道高反应性和哮喘加重的重要因素.有很多因素导致气道平滑肌增生及肥大,如炎症介质、生长因子、细胞因子、细胞外基质蛋白和遗传因子等.最近的研究揭示气道平滑肌也是炎症介质的重要来源.建议在哮喘发病早期应用激素吸入治疗.     

气道平滑肌细胞在哮喘气道重塑中的作用

气道重塑是气道慢性炎症的结果,包括气道壁增厚和基质沉积、胶原沉积、上皮下纤维化、平滑肌增生和肥大、肌成纤维细胞增殖及黏液腺、杯状细胞化生及增生、上皮下网状层增厚、微血管生成等病理改变.在这些病理变化中,气道平滑肌的改变被认为是导致气道高反应性和哮喘加重的重要因素.有很多因素导致气道平滑肌增生及肥大,如炎症介质、生长因子、细胞因子、细胞外基质蛋白和遗传因子等.最近的研究揭示气道平滑肌也是炎症介质的重要来源.建议在哮喘发病早期应用激素吸入治疗.     

HGF对TGF-β1诱导尿道瘢痕成纤维细胞α-SMA及细胞外基质过度合成的保护作用

目的 探讨HGF对TGF-β1诱导尿道瘢痕成纤维细胞α-SMA及细胞外基质过度合成的保护作用.方法 收集尿道下裂术后瘢痕组织的标本,进行尿道瘢痕成纤维细胞的分离和培养.待细胞生长成单层后,以胰蛋白酶消化传代.取第四代成纤维细胞用于实验,当细胞达到80%融合时,培养液中加入TGF-β1(5ng/ml)及HGF(10～40ng/ml).培养72 h后,用RT-PCR检测各组α-SMA mRNA的变化;ELISA测定细胞Ⅰ、Ⅲ型胶原及纤维结合素的表达.结果 TGF-β1能显著诱导α-SMA m-RNA表达.随HGF的加入,α-SMA m-RNA的表达则明显受到抑制(P＜0.05),且随HGF浓度的升高其阻抑作用呈逐渐增强趋势.对照组、单纯TGF-β1组、加入TGF-β1与10、20、40ng/ml HGF组的Ⅰ型胶原A值分别为0.51±0.04、0.78±0.05、0.71±0.02、0.63±0.03、0.57±0.02,Ⅲ型胶原A值分别为0.12±0.01、0.29±0.02、0.21±0.02、0.14±0.01、0.08±0.01,纤维结合素A值分别为0.24±0.03、0.51±0.02、0.49±0.01、0.38±0.02、0.28土0.01.表明TGF-β1同样能诱导Ⅰ、Ⅲ型胶原及纤维结合素的表达(P＜0.01),而HGF则可以有效地阻抑其表达,其效应呈剂量依赖性(P＜0.05).结论 HGF对TGF-β1诱导的尿道瘢痕成纤维细胞α-SMA及细胞外基质过度合成具有抑制作用.这为临床预防和治疗尿道瘢痕狭窄提供了理论依据.

Abstract：

Objective To examine the inhibitory effects of HGF on TGF-β1 induced a-SMA and extracellular matrix synthesis in cultured fibroblasts derived from urethral scar. Methods Fibroblasts isolated from urethral scar were cultured ex vivo. After the fibroblasts reached confluence, cells were detached using trypsin/ethylenediamine tetra-acetic acid. All experiments were performed using the cells at the fourth passage. At 80% confluence, TGF-β1 (5 ng/ml) and HGF (10-40 ng/ml) were added to the culture medium. After 72 hours co-incubation, the mRNA of a-SMA was studied by RTPCR. The productions of collagen Ⅰ, Ⅲ and fibronectin in supernatants were also examined using ELISA. Results TGF-β1 markedly induced a-SMA mRNA expression in cultured fibroblasts. However, HGF could abrogated TGF-β1-induced a-SMA mRNA expression in a dose-dependent manner (P＜0. 05). The levels of collagen type Ⅰ were 0. 51 ± 0. 04,0. 78 ± 0. 05,0. 71 ± 0. 02,0. 63 ± 0. 03, and 0. 57 ± 0. 02 in control, TGF-β1, TGF-β1 + 10 ng/ml HGF, TGF-β1 + 20 ng/ml HGF, and TGF-β1 +10 ng/ml HGF group, respectively. The levels of collagen type Ⅲ were 0. 12 ± 0. 01,0. 29 ± 0. 02,0. 21 ± 0. 02,0. 14 ± 0. 01, and 0. 08 ± 0. 01 in control, TGF-β1, TGF-β1 + 10 ng/ml HGF, TGF-β1 +20 ng/ml HGF, and TGF-β1 + 10 ng/ml HGF group, respectively. And the levels of fibronectin were 0.24±0.03,0.51 ± 0.02,0.49 ± 0.01,0.38 ± 0.02,0.28 ± 0.01 in control, TGF-β1, TGF-β1 +10 ng/ml HGF, TGF-β1 + 20 ng/ml HGF, and TGF-β1 + 10 ng/ml HGF group, respectively. TGF-β1 significantly stimulated collagen Ⅰ, Ⅲ and fibronectin production in fibroblasts (P＜0. 01 ). However,HGF could reduced abrogated the up-regulation of collagen Ⅰ, Ⅲ and fibronectin induced by TGF-β1 in a dose-dependent manner (P＜0. 05). Conclusions HGF can effectively inhibit TGF-β1 induced aSMA and extracellular matrix synthesis in cultured fibroblasts derived from urethral scar.     

Serum levels of carboxyterminal propeptide of type I procollagen, aminoterminal propeptide of type III procollagen and laminin P1 in Duchenne muscular dystrophy

The striking proliferation of connective tissue in Duchenne muscular dystrophy is attributed, besides other components of the extracellular matrix, to an increase of endomysial and perimysial type III and type I collagen. We investigated if muscle fibrosis correlates to an increased serum concentration of procollagen I or HI. Therefore, we measured the serum levels of carboxyterminal propeptide of type I procollagen, aminoterminal propeptide of type III procollagen and laminin P1 in 20 boys with progressive muscular dystrophy (16 definite Duchenne muscular dystrophy, 2 suspected of Duchenne muscular dystrophy, 2 Becker muscular dystrophy). In contrast to collagen I and III the expression of laminin in the basement membrane is known to be normal in Duchenne muscular dystrophy. There was no significant alteration of serum concentration of procollagen ni N-peptide, procollagen I C-peptide and laminin PI in boys with Duchenne muscular dystrophy. Measuring these parameters is not useful for investigating the extent of muscle fibrosis or for monitoring the effect of therapeutic trials such as steroid treatment.     

Three-dimensional co-culture model of enterocytes and primary enteric neuronal tissue

Aim The aim of this study was to establish a three-dimensional model of the innervated mucosal barrier using a co-culture of an enterocyte cell line and enteric glial and nerve cells. Such a model might form the basis for further studies of interactions between the single compartments of the bowel wall, as well as of extrinsic influences on intestinal development and plasticity.Methods Isolated and dissociated myenteric plexus was resuspended in either collagen or extracellular matrix (ECM) solutions. After incubation at 37°C the solution gelled and formed stable plugs where neurons and glial cells reaggregated to form secondary neuronal networks. HT-29-enterocytes were seeded on top of the gels either immediately (collagen, ECM), or after adding a thin layer of collagen II (ECM).Results While the neuronal tissue formed complex networks within the gel, the enterocytes on top of the gels grew differently depending on the substrate and innervation. So enterocytes on ECM gels did not grow to confluence, while on collagen gels or on ECM plus collagen larger patches and increasing confluence could be observed. In general HT-29 grew better on innervated gels than on gels with no neuronal tissue.Conclusions With the presented model of different compartments of the bowel wall, various parameters of intercellular dependencies and influences can be observed in vitro. Moreover, the first results are also steps towards developing an innervated gut wall in vitro which might be able to restore functional capacity in infants with short bowel syndrome or other disorders that severely impair bowel function.S. Bainczyk and C. Hagl contributed equally to the study     

Achondrogenesis Type IA (Houston-Harris): a still-unresolved molecular phenotype.

Achondrogenesis type IA (Houston-Harris) is an extremely rare lethal chondrodysplasia with a characteristic severe disarrangement of endochondral ossification. The growth plate cartilage completely lacks columnar-zone formation and shows chondrocyte expansion due to intracellular vacuoles. This article on a new case of achondrogenesis type IA confirms these findings and demonstrates, on the ultrastructural level, the retention of fine fibrillar material within the rough endoplasmic reticulum (rER). Molecular analysis in the presented case of achondrogenesis type IA did not reveal mutations in the COL2A1 and SLC26A2 genes, which are known to cause achondrogenesis types IB and type II. Although the extracellular cartilage matrix was severely altered, all of the investigated matrix molecules (collagens, aggrecan, matrilins, cartilage oligomeric protein [COMP]) showed a normal distribution pattern. The only exception was type-X collagen, which was significantly reduced. Overall, our study suggests a disturbance in cartilage matrix assembly in the present case due to the retention of some sort of matrix component within the rER. Presumably, as a consequence of this event, processes of chondrocyte maturation and differentiation and endochondral bone formation are severely affected in this case of achondrogenesis type IA.