• Applied Microscopy
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• v.26 no.2
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• pp.177-195
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• 1996

Fine structure of the processes of intramembranous ossification and endochondral ossification at the tip of the distal phalanx of human fetuses was studied by electron microscopy. In 50 mm fetus, intramembranous ossification of the tip of cartilaginous phalanx was first noted. The osteoblasts of the perichondral zone of tip of cartilaginous phalanx started to lay down a thick membranous bony lamella. Most of the hypertrophied chondrocytes in the marginal parts of tip of the distal phalanx remained viable after being embeded in mineralized cartilaginous septa. The tuberosity of the distal phalanx was formed by membranous bony trabeculae on the exterior of the subperiosteal cap at 80 mm fetus. At this stage endochondral ossification was first observed in distal extremity of the distal phalanx. The maority of hypertrophied chondrocytes in the center of distal extremity appeared to be disintegrating. Resorption of calcified matrix was undertaken by perivascular cells and chondroclasts. From the periosteum, zone of calcification, vascular sprouts expanded within a recently opened lacunae, and the invading osteoblasts laid down osteoid and bone. After 120 mm fetus, endochondral and subperiosteal ossification proceeded in only one direction, just proximally. These findings demonstrate that intramembranous ossification, calcification, and endochondral ossification start at tip of the distal phalanx instead of at the center of the shaft, as was the case in other long bones.

• Applied Microscopy
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• v.24 no.1
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• pp.59-76
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• 1994

Fine structure of the distal femoral epiphysis of growing mouse was studied by electron microscopy. The first morphological evidence of developing secondary center of ossification in the distal femoral epiphysis was found at newborn mouse. Ossification center was in the form of multiple foci of calcification and its cells were represented by remnant of degenerated cells within large lacunae that were separated by mineralized cartilaginous septa. Endochondral ossification beneath the articular cartilage proceeded in a less orderly manner than metaphyseal endochondral ossification. Columns of hypertrophied chondrocytes were not distinctly parallel to intercellular mineralized septa in all direction. Hypertrophied chondrocytes in the inner zone of the epiphseal center of ossification showed disintegrated. Resorption of mineralized cartilaginous septa was undertaken by perivascular cells and multinucleated chondroclasts. Resorption of the calcified cartilage was restricted to the region of ruffled border of the chondroclast. Growth along the metaphyseal side of the epiphyseal center of ossification was different from that along the articular surface. As the secondary center expanded toward the metaphyseal side, many vascular buds penetrated unmineralized cartilaginous septa and invaded viable chondrocytes. Many hypertrophied chondrocytes bodering the metaphyseal side of bone center remained viable after they became embedded in mineralized cartilaginous septa. This result suggested that the hypertrophied.

• Korean Journal of Veterinary Research
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• v.31 no.2
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• pp.143-154
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• 1991

The present study was undertaken to provide basic data on fetal endochondral ossification for the native Korean cattle femur. This study was determined to the both earliest stages of chondrification and ossification by histochemical methods. The forty-five pairs of femur, from a series of embryos and fetuses ranging from 11 to 100mm in crown-rump(C-R) length, were used. These samples were divided into 9 groups. The groupings were based on C-R length, as the first grouping being 11~20mm, the second grouping being 21~30mm and so on. The results were as follows: 1. Alcianophility and PAS reaction were markedly increased in the perichondrium and interterritorial matrix in the 3rd group(C-R length 31~40mm). These reactions were decreased in the territorial matrix and in the adjacent area to the cartilage canal in the 5th group(C-R length 51~60mm). 2. Calcium deposits and collagen substances were observed initially in the 3rd group(C-R length 31~40mm). The calcium deposits and calcified cores were observed in the trabeculae of the proximal epiphyseal plate of the femur in the 8th group(C-R length 81~90mm).

• Molecules and Cells
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• v.25 no.1
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• pp.1-6
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• 2008

Osteoarthritis (OA), one of the most common skeletal disorders characterized by cartilage degradation and osteophyte formation in joints, is induced by accumulated mechanical stress; however, little is known about the underlying molecular mechanism. Several experimental OA models in mice by producing instability in the knee joints have been developed to apply approaches from mouse genetics. Although proteinases like matrix metalloproteinases and aggrecanases have now been proven to be the principal initiators of OA progression, clinical trials of proteinase inhibitors have not been successful for the treatment, turning the interest of researchers to the upstream signals of proteinase induction. These signals include undegraded and fragmented matrix proteins like type II collagen or fibronection that affects chondrocytes through distinct receptors. Another signal is proinflammatory factors that are produced by chondrocytes and synovial cells; however, recent studies that used mouse OA models in knockout mice did not support that these factors have a role in the central contribution to OA development. Our mouse genetic approaches found that the induction of a transcriptional activator Runx2 in chondrocytes under mechanical stress contributes to the pathogenesis of OA through chondrocyte hypertrophy. In addition, chondrocyte apoptosis has recently been identified as being involved in OA progression. We hereby propose that these endochondral ossification signals may be important for the OA progression, suggesting that the related molecules can clinically be therapeutic targets of this disease.

• Korean Journal of Veterinary Research
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• v.32 no.3
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• pp.309-319
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• 1992

This study was undertaken to establish the sequence of development of ages and its time of the fetal endochondral ossification in the scapula of the Korean native cattle. This study was also designed to confirm through histological observation the earliest stages of both chondrification and ossification. Thirty eight scapulae, a series of embryos and fetuses from the pregnant Korean native cattle ranging from 11 to 110mm in crown-rump (C-R) length, were used. The following results were obtained. The ossification center was observed in the supra- and infra- spinous fossa in the 5th group (CRL 51-60mm), that was markedly ossified in the 6th group (CRL 61~70mm) by Alizarin red S stain. The chondrogenic center of scapula was observed in the 1st group (CRL 11~20mm). The primary ossification center was presented in the 4th group (CRL 41~50mm). In the 5th group(CRL 51~60mm), the endochondral ossification progressed actively. Alcianophility was markedly increased in the interterritorial matrix in the 3rd group (CRL 31~40mm. However this reaction was markedly decreased in the interterritorial matrix the adjacent portion to the marrow cavity and trabecula in the 5th group (CRL 51~60mm).

• Journal of Life Science
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• v.12 no.1
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• pp.1-8
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• 2002

Antlers from deer species are alternative animal by-products. Due to the oriental trade, the velvet antler industry is rapidly emerging in North America. The unique biological property of antler wish a deciduous natural phenomenon offers the valuable model of biomedical research. Growing antlers showed different structures according to cell populations consisting of mesenchymes, chondroblasts, chondrocytes and osseous tissues from distal to proximal portions of main beam. Their structures were different from two tissues, cartilage and bone, in growing antlers. Zone of maturing ants calcifying chondrocytes referred as upper section was invaded by osteoblasts indicating the occurrence of endochondral ossification. The cartilaginous tissues were gradually replaced by osseous tissues downward. The bony tissues referred as the middle and base sections in this thesis contained spongy bone and cortical bone structure in the difference of the degree of mineralization antral the thickness of cortical bony in adjacent to outer velvet layer. In addition, the endocrinological regulators such as testosterone, prolactin, growth hormones and other growth factors are actively involved in the unique deciduous nature shown in the growth and development of antler.

• Korean Journal of Veterinary Research
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• v.33 no.2
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• pp.189-198
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• 1993

The present study was undertaken to provide basic data on endochondral ossification for the axis in developing Miniature Schnauzers. This study was determined to the morphological features and development of growth plast in the axis of this experimental animals by histological and histochemical methods. The axis from 2 healthy Miniature Schnauzers(postnatal 6hr, 5week) was used. The obtained results were as follows : 1. In 5-week-old Miniature Schnauzer, the axis consisted of 4 separate ossification centers : centrum l, intercentrum 2, centrum 2 and epiphysis. Intercentrum 2 was intercalated between centrum 1 cranially, centrum 2 caudally. 2. The space of centrum 1 was more broader than the other ossification centers. 3. The zone of reserved chondrocytes was more extensive than the zone of proliferative chondrocytes, trabeculation was weakly observed, however, the proximal epiphyseal plate of axis was actively trabeculation observed in the zone of calcified chondrocytes. 4. Eighteen columns of chondrocytes were observed in the centrum 1 and five to seven columns of chondrocytes were observed in the centrum 2 of Miniature Schnauzer(postnatal 5 week) 5. A positive reaction to alcianophility was observed in all the territorial matrix at the zone of hypertrophic chondrocytes in this experimental animals.

• Molecules and Cells
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• v.24 no.2
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• pp.177-184
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• 2007

Approximately 200 individual skeletal elements, which differ in shape and size, are the building blocks of the vertebrate skeleton. Various features of the individual skeletal elements, such as their location, shape, growth and differentiation rate, are being determined during embryonic development. A few skeletal elements, such as the lateral halves of the clavicle and parts of the skull are formed by a process called intramembranous ossification, whereby mesenchymal cells differentiate directly into osteoblasts, while the majority of skeletal elements are formed via endochondral ossification. The latter process starts with the formation of a cartilaginous template, which eventually is being replaced by bone. This requires co-regulation of differentiation of the cell-types specific for cartilage and bone, chondrocytes and osteoblasts, respectively. In recent years it has been demonstrated that Wnt family members and their respective intracellular pathways, such as non-canonical and the canonical $Wnt/{\beta}$-catenin pathway, play important and diverse roles during different steps of vertebrate skeletal development. Based on the recent discoveries modulation of the canonical Wnt-signaling pathway could be an interesting approach to direct stem cells into certain skeletal lineages.

• Journal of Embryo Transfer
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• v.33 no.1
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• pp.31-40
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• 2018

Developmental aspects of chicken embryos showed dramatic difference compared with those of mammals and consequently, such difference in various developmental events leads to different feasibility in both clinical and industrial application. We have concentrated on the studies for using of chicken bone marrow cells and currently we found number of unique cellular properties. Through this article, we reviewed characteristics and cell signaling of osteogenic cells during endochondral ossification in chicken long bone.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.68-79
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• 1996

To investigate the efficiency of a fibrous collagen membrane(FCM) composed of bovine skin type I atelocollagen as a carrier for BMP, partially purified bovine BMP/FCM($0.3mg/10{\times}5{\times}1mm$) composites were implanted into the dorsal subcutaneous tissue of rats. FCM alone was also implanted as a control. The implants were harvested at 1, 2, 3, and 10 weeks after implantation, then prepared for routine light microscopic observation. The FCM alone did not induce osteogenesis and revealed no specific foreign body reaction nor was there any definite resorptive evidence for 10 weeks after implantation, while the BMP/FCM composites induced favorable bone formation in a process that resembled an endochondral and direct ossification mode. At 10 weeks, the well formed bone confined to embedded collagen fibers revealed hematopoietic marrow between bony trabeculae without evidence of resorptive or degenerative changes . These findings support the suggestion that BMP may induce undifferentiated mesenchymal cells into either chondroblasts or osteoblasts or both independantly according to the chemico- physical characteristics of the carrier, which develops the endochondral and/or direct bone formation process, and suggest that the FCM may be a favorable carrier for BMP.