Electron microscopic studies on chick limb cartilage differentiated in tissue culture (original) (raw)
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An ultrastructural study of early chondrogenesis in the chick wing bud
Developmental Biology, 1972
The differentiation of cartilage in the embryonic chick wing has been examined with the electron microscope with particular attention to ultrastructural changes occurring at the stage when the cartilage-forming region can first be detected using the light microscope, and at the stage when extracellular metachromatic matrix can first be detected using histological stains. Later stages in limb cartilage differentiation were not examined since these have been described by previous authors. Prior to the development of the cartilage-forming region, the cells have very broad contacts between cells bodies. With the development of the cartilage-forming region, cell contacts become increasingly restricted until, in well developed cartilage, most contacts are through filopodia. With the change in the nature of cell contacts, there appears to be an increase in the extracellular space and an increase in the number of 50-70A microfilaments within the cells. The extracellular materials that could be found in electron micrographs in well developed cartilage could each be found in the extracellular space prior to the development of the cartilageforming region, and no abrupt and profound change in rate of synthesis of any material was detected. The development of extracellular metachromatic matrix detectable with histological stains apparently is due to the accumulation of extracellular materials above some threshold concentration.
Electron microscopic studies on developing cartilage
Development, 1972
A procedure for the study of glycogen in the same cell, under both light and electron microscopes is described. The synthesis and accumulation of glycogen is a feature of chondrogenesis in the mouse epiphyseal cartilage and the amount of glycogen increases with the progress of differentiation. In contrast, no glycogen was detected in differentiating epiphyseal cartilage of the chick at any stage; except for a small amount of glycogen in the chick cartilage cells of the diaphysis. Because of this difference it is suggested that presence of glycogen is not essential for cartilage differentiation.
Cartilage canals in the chicken embryo: ultrastructure and function
Anatomy and Embryology, 2004
In this study the detailed morphology and the function of cartilage canals in the chicken femur are investigated. Several embryonic stages (e 13.5, 16, 19, and 20) are examined by means of light microscopy, electron microscopy (TEM), and immunohistochemistry (VEGF, type I and II collagen). Our results show that cartilage canals originate from the perichondrium and form a complex pattern. Two types of canals are distinguishable: shell canals and communicating canals. Shell canals are in the reserve zone and are arranged in successive layers. Communicating canals spring from the shell canals and pass down into the proliferative zone and into the hypertrophic zone. These canals are conical shaped and are orientated nearly in parallel to the long axis of the femur. Cartilage canals comprise venules, arterioles, capillaries (mature and immature), and undifferentiated mesenchymal cells. No canal wall in the sense of an epithelium is elaborated. VEGF is detected in both types of canals and macrophages are found at the end of the cartilage canals. We conclude that the growth factor stimulates angiogenesis and that the latter cells erode the matrix ahead of the canals and thus enable the advancement of the vessels. The results clearly show that the canal matrix differs from the remaining cartilage matrix. The canal matrix contains type I collagen, few type II collagen fibrils and proteoglycans are lacking. In contrast, in the cartilage matrix type II collagen and proteoglycans are abundant but no type I collagen is found. Communicating canals are surrounded by a distinct layer of type I collagen indicating that osteoid is formed around these canals. Hypertrophic chondrocytes label for type I collagen and it seemed possible that chondrocytes adjacent to the communicating canals differentiate into bone-forming cells. Our results provide evidence that cartilage canals are involved in nourishment of the cartilage as well as in the ossification process.
Matrix changes during long-term cultivation of cartilage (organoid or high-density cultures)
Histology and histopathology, 1993
In high density (organoid or micromass) cultures of prechondrogenic mesenchymal cells from limb buds of 12-day-old mouse embryos typical cartilaginous tissue develops after 3 days. Immunomorphological investigations have shown that it contains the typical components of the cartilaginous matrix, such as collagen type II and cartilage-specific proteoglycans. After a 2-week cultivation period hypertrophic cartilage cells develop to an increasing extent. Many of these cells as well as normal chondroblasts detach from the matrix from the 2nd week in vitro onwards to assume a fibroblast-like appearance. At the same time thick (25-65 nm) collagenous fibrils occur at the surface of these cells. These thick fibrils contain collagen type I, as shown by immunomorphology. Hence, in these older cartilage cultures chondroblasts change their synthesis programme or direction of differentiation. Consequently, a model for the study of "dedifferentiation" of cartilage and possibly also trans...
Mechanical Modulation of Cartilage Structure and Function During Embryogenesis in the Chick
Annals of Biomedical Engineering, 2004
The mechanical behavior of cartilage is intimately related to its biochemical composition, and tissue composition is known to be influenced by its local mechanical loading environment. Although this phenomenon has been well-studied in adult cartilage, few investigations have examined such structurefunction relationships in embryonic cartilage. The goal of this work was to elucidate the role of mechanical loading on the development of cartilage composition during embryogenesis. Using an embryonic chick model, cartilage from the tibiofemoral joints of immobilized embryos was compared to that of controls. The normal time course of changes in glycosaminoglycan/DNA and hydroxyproline/DNA were significantly influenced by loading history, with the most pronounced effects observed between days 9 and 14 during the period of most rapid increase in motility in control embryos. Stress-relaxation tests conducted on samples from day 14 indicate that the effects of embryonic immobilization on cartilage matrix composition have direct consequences for the mechanical behavior of the tissue, resulting in compromised material properties (e.g. 50% reduction in E inst). Because embryogenesis provides a unique model for identifying key factors which influence the establishment of functional biomechanical tissues in the skeleton, these data suggest that treating mechanical loading as an in vitro culture variable for tissue engineering approaches to cartilage repair is likely to be a sound approach.
Developmental Dynamics, 1992
In this study, an organ culture system is defined which demonstrates complete loss of cartilage matrix from embryonic chick tibiae. Efficient loss of the cartilage matrix occurs within 30 days of serum-free culture only when the intact tibiae containing bone, marrow, and cartilage tissue are cultured. During organ culture nonhypertrophic chondrocytes become hypertrophic and stain positively for type X collagen and alkaline phosphatase. The cartilage loses Safranin 0 staining, and finally all cartilage matrix disappears leaving the bony collar and marrow cells. If the tibia1 cartilage is separated from the bony collar and cultured alone in serum-free medium, the nonhypertrophic chondrocytes also hypertrophy; the matrix loses Safranin 0 staining; however, some components of the matrix including type X collagen still remain after 30 days.
The development of embryonic bone and cartilage in tissue culture
PubMed, 1983
Embryonic chick long bone develops in a series of temporally controlled, cellular events and involves the integration of at least three distinctly different sets of cells: collar osteoblasts, core osteoblasts, and resorptive or osteoclastic cells. The morphology of the long bones is established by the developing cartilage rudiment or model. All of these events seem to be influenced by positional cues. The cultivation of all of these cells and their presumptive progenitor cells potentially allows a detailed analysis of their individual and collective phenotypic traits. Future studies can include how long bones form, how bone-forming and bone-resorbing cells interact, and how osteogenic cells influence each other throughout each stage of their respective developmental lineages.
Extracellular matrix of ostrich articular cartilage
BIOCELL, 2005
The composition and organization of the extracellular matrix of ostrich articular cartilage was investigated, using samples from the proximal and distal surfaces of the tarsometatarsus. For morphological analysis, sections were stained with toluidine blue and analyzed by polarized light microscopy. For biochemical analysis, extracellular matrix components were extracted with 4 M guanidinium chloride, fractionated on DEAE-Sephacel and analyzed by SDS-PAGE. Glycosaminoglycans were analyzed by electrophoresis in agarose gels. Structural analysis showed that the fibrils were arranged in different directions, especially on the distal surface. The protein and glycosaminoglycan contents of this region were higher than in the other regions. SDS-PAGE showed the presence of proteins with molecular masses ranging from 17 to 121 kDa and polydisperse components of 67, 80-100, and 250-300 kDa in all regions. The analysis of glycosaminoglycans in agarosepropylene diamine gels revealed the presence of only chondroitin-sulfate. The electrophoretic band corresponding to putative decorin was a small proteoglycan containing chondroitin-sufate and not dermatan-sulfate, unlike other cartilages. The higher amounts of proteins and glycosaminoglycans and the multidirectional arrangement of fibrils seen in the distal region may be correlated with the higher compression normally exerted on this region.
Location of 64K collagen producer chondrocytes in developing chicken embryo tibiae
Molecular and Cellular Biology
The synthesis of a new low-molecular-weight collagen by cultured chicken embryo chondrocytes has been recently demonstrated (Capasso et al., Exp. Cell Res. 142:197-206, 1982; Gibson et al., J. Cell Biol. 93:767-774, 1982; Schmid and Conrad, J. Biol. Chem. 257:12444-12450, 1982). In this paper we report results on the location of chondrocytes synthesizing this new collagen (64K collagen) in the developing chicken embryo. The 64K collagen is synthesized in very large amounts by cells concentrated at the diaphysis of 9-day-old and at the epiphysis of 17-day-old embryo tibiae. These regions are characterized by a remodeling of the cartilage matrix leading to the replacement of the cartilage with bone tissue; therefore, this collagen appears to be a marker of a specific developmental stage of chondrocytes. The origin of cells competent for the synthesis of the 64K collagen is also discussed.