Bovine achondrogenesis: evidence for defective chondrocyte differentiation

Immunohistochemical Examination of Epiphyseal Growth Plates of Japanese Brown Cattle with Chondrodysplasia

A new type of inherited chondrodysplasia is described in Japanese Brown cattle, but the basic defects of the epiphyseal growth plate (EGP) in the limb long bones, and proliferation and differentiation of the chondrocytes in the EGP, are not yet understood. In the present study, the EGPs of the limb long bones in eight cases of chondrodysplasia and four normal (control) cattle were examined histologically and immunohistochemically. In the control cattle, proliferative chondrocytes (PCs) and hypertrophic chondrocytes (HCs) were arranged in columns parallel to the long axis of the bone, and HCs were situated on the metaphyseal side of the EGP. In all the affected cattle, many chondrocytes with a hypertrophic appearance were detected in the inner areas of the central portion of the EGP. The PC columns were short and arranged irregularly. Bone tissue and small blood vessels were found frequently in these areas. Six affected cattle showed complete EGP-closure. Backscattered electron (BSE) imaging showed that the calcified cartilage matrix was restricted to the lower region of the hypertrophic zone (HZ) of the EGP in the control cattle, while the calcified cartilage matrix and bone tissue were scattered in the inner areas of the EGP in all the chondrodysplastic cattle. Immunohistochemistry revealed type X collagen in the HCs and cartilage matrix of the HZ in the control cattle. In all the affected cattle, type X collagen was detected in apparently hypertrophic chondrocytes in the inner areas of the EGP. Type II collagen was detected in the entire EGP in all the affected cattle, as in the controls. BrdU (5-bromo-2'-deoxyuridine), injected intravenously 1h before euthanasia was detected in many PCs in the EGP in the control cattle; none, however, was detected in the central portion of the EGP in any affected animal. These observations indicate that differentiation into HCs and calcification of cartilage matrix occur in the inner areas of the central portion of the EGP in chondrodysplasia of Japanese Brown cattle. Differentiation into the HCs at this abnormal site may be caused by the inadequate proliferation and disorganization of the PCs. Premature EGP-closure, observed commonly in chondrodysplasia of Japanese Brown cattle, was thought to be caused by replacement of the calcified cartilage in the inner areas of the EGP by bone tissue.

Delivery of dexamethasone, ascorbate, and growth factor (TGF β-3) in thermo-reversible hydrogel constructs embedded with rabbit chondrocytes

The aim of this study was to assess the efficacy of poly(N-isopropylacrylamide-co-acrylic acid) (p(NiPAAm-co-AAc)) as an injectable drug delivery vehicle and a cell therapeutic agent in the form of a supporting matrix for the chondrogenic differentiation of rabbit chondrocytes. The p(NiPAAm-co-AAc) hydrogel itself without specific differentiation-inducing drugs was used as a control in order to determine the effects of these materials on chondrogenic differentiation. The level of cartilage associated extracellular matrix (ECM) proteins was examined by immunohistochemical staining for collagen type II as well as Safranin-O and Alcian blue (GAG) staining. These results highlight the potential of a thermo-reversible hydrogel mixed with chondrocytes and differentiation materials as an injectable delivery vehicle for use in neocartilage formation.

Congenital chondrodysplastic dwarfism with dyshematopoiesis in a holstein calf

A holstein calf with congenital chondrodysplastic dwarfism was histopathologically examined. The head of the calf was relatively flat giving a dog-like appearance with its short nose and sloping forehead. Limb bones were dumbbell-like with short diaphysis and hypertrophied metaphyses. Bone marrow was pale, whitish and fatty. In the metaphyseal plates most of chondrocytes were pyknotic with swollen and ghost-like cytoplasm, and were irregularly arranged. Column of calcified cartilage were poorly formed losing comb-like structure. Bone marrow was ischemic with poor hematopoiesis and was moderately replaced by adipose tissue. In articular cartilage, most of chondrocytes were degenerated with ghost-like cytoplasm. Many cartilage canals and occasional bone marrow-like structure were formed. The characteristics lesions of the calf were chondrodysplasia and dyshematopoiesis.

Congenital defects of the bovine musculoskeletal system and joints

A variety of structural and functional congenital defects affecting the central nervous system of cattle have been identified. This article discusses specific defects of the central nervous system. Spastic and paralytic, metabolic, and storage diseases are reviewed.

Achondrogenesis-hypochondrogenesis: the spectrum of chondrogenesis imperfecta. A radiological, ultrasonographic, and histopathologic study of 23 cases

In the classification of lethal osteochondrodysplasias, achondrogenesis and hypochondrogenesis have recently received special attention. We describe 23 cases representing the different subtypes. Within the classical type I (Parenti-Fraccaro) two distinct disorders can be recognized: type IA (Houston-Harris) and type IB (Fraccaro). The classical type II (Langer-Saldino) and hypochondrogenesis represent phenotypic variants of one disorder in which type II is the most severe form and hypochondrogenesis the mildest form, while transitional forms exist. It is likely that a basic defect in cellular function of the chondrocyte results in a deficient cartilage matrix and in disorganized enchondral ossification.

Abnormal ossification in thanatophoric dysplasia

Thanatophoric dysplasia (TD) is a lethal human bone dysplasia characterized by severe dwarfism. It pathogenesis is thought to involve an abnormal ossifying fibrous tissue that disrupts the skeletal growth plate. We employed a combined morphologic, immunohistochemical and biochemical approach to better define the nature of this tissue in growth plate cartilage from 15 TD fetuses and infants in whom the abnormality was observed. The tissue was organized into tufts comprised of a cap of interstitial connective tissue, a transition region containing preosteoblastic cells near the cap and osteoblastic cells near the base, and a mineralized base which formed the subchondral bone trabeculae. The morphology of the cells and the presence of type I collagen in all regions of the tufts suggested that they were foci of membraneous ossification. However, elements of cartilage matrix (type II collagen, proteoglycan, link protein) were identified in the pericellular matrix of the osteoblastic cells and adjacent osteocytic cells. These observations suggest that a peculiar form of ossification occurs in the TD growth plate and may be involved in the pathogenesis of the disorder.