Memoirs: The Posterior End of Meckel's Cartilage and Related Ossifications in Bony Fishes

1937 ◽  
Vol s2-80 (317) ◽  
pp. 1-38
Author(s):  
R. WHEELER HAINES

1. In modern Dipnoi (Protopterus) the membrane bones are separated by connective tissue from Meekel's cartilage, and there is no endochondral or perichondral bone. The cartilage grows evenly over its whole extent. 2. In Polypterus a large articular ossifies the posterior end of the cartilage, including the retro-articular process, and spreads into the neighbouring connective tissues. 3. In Elops the joint surface is carried partly by the articular, and partly by the retro-articular, a special ossification of the retro-articular process. 4. In most teleosts (Mugil, Sardina, Trigla) the articular is absent and the angular invades the perichondrium and cartilage to form the joint surface. Special growth zones of flattened cells are formed in the cartilage which by their growth carry the retro-articular, angular, and dentary away from one another, stability of the jaw being maintained by new growth of the membranous parts of the bones. 5. Endochondral bone is reduced or absent in some specialized fishes (Tetrodon, Notopogon). 6. The sesamoid articular of teleosts is a separated part of the angular which gives insertion to the adductor mandibulae muscle. 7. An attempt is made to follow the evolution of Meckel's cartilage and the related ossifications by a comparison of the early Dipnoi, Crossopterygii, and Amphibia described in the literature with modern forms.

Fossil Record ◽  
2005 ◽  
Vol 8 (1) ◽  
pp. 13-35 ◽  
Author(s):  
G. C. Young ◽  
H.-P. Schultze

Abstract. Osteichthyan remains described from two localities in Central Australia (Mount Winter, Amadeus Basin, and southern Toomba Range, Georgina Basin) include the dipnoan Amadeodipterus kencampbelli n. gen., n. sp., the osteolepidid Muranjilepis winterensis n. gen., n. sp., and the onychodontid Luckeus abudda n. gen., n. sp., as well as indeterminate holoptychiid scales, osteolepidid scales of a new type from the Georgina Basin locality, and indeterminate onychodontid remains from both localities. Amadeodipterus n. gen. is a short-headed dipterid dipnoan with bones A and H enclosed into the skull roof; Muranjilepis n. gen. is a small form with short postparietal and parietoethmoidal shields, large orbits, and large pores of the sensory line system. It is closest to Thursius, and some Chinese osteolepidid material. Luckeus n. gen. is based on an onychodontid lower jaw with Meckel’s cartilage separately ossified perichondrally from the dentary and infradentary, and carrying the parasymphysial tooth whorl. Different osteichthyan taxa at the two localities indicate a difference in age and/or palaeoenvironment within the Early-Middle Devonian. Knochenfischreste aus zwei Fundorten Zentralaustraliens (Mount Winter, Amadeus Becken und südlicher Toomba Rücken, Georgina Becken) umfassen den Lungenfisch Amadeodipterus kencampbelli n. gen., n. sp., den osteolepididen Sarcopterygier Muranjilepiswinterensis n. gen., n. sp., und den onychodontiden Sarcopterygier Luckeus abudda n. gen., n. sp., sowie unbestimmte holoptychiide und osteolepidide Schuppen eines neuen Typs aus dem Fundort im Georgina Becken und unbestimmte onychodontide Reste von beiden Fundorten. Amadeodipterus n. gen. ist ein kurz-schädeliger Lungenfisch, bei dem die Knochen A und H in das Schädeldach miteingeschlossen sind. Bei Muranjilepis n. gen. handelt es sich um einen kleinen Osteolepididen mit kurzem Postparietal- und Parietoethmoidal-Schild, großen Augenhöhlen und großen Poren des Sinneskanalsystems; er ist am nächsten mit Thursius und einigen chinesischen Osteolepididen verwandt. Ein unbestimmter onychodontider Unterkiefer zeigt ein wahrscheinlich primitives Merkmal in der perichondralen Verknöcherung des Meckelschen Knorpels getrennt von Dentale und Infradentale, der die Unterlage der parasymphysialen Zahnspirale bildet. Verschiedene Knochenfischtaxa treten an den beiden Lokalitäten auf; das deutet auf unterschiedliches Alter und/oder Palaeoenviroment an der Unter-Mitteldevongrenze zwischen beiden Lokalitäten hin. doi:10.1002/mmng.200410002


2021 ◽  
Vol 8 (11) ◽  
Author(s):  
Richard P. Dearden ◽  
Sam Giles

The teeth of sharks famously form a series of transversely organized files with a conveyor-belt replacement that are borne directly on the jaw cartilages, in contrast to the dermal plate-borne dentition of bony fishes that undergoes site-specific replacement. A major obstacle in understanding how this system evolved is the poorly understood relationships of the earliest chondrichthyans and the profusion of morphologically and terminologically diverse bones, cartilages, splints and whorls that they possess. Here, we use tomographic methods to investigate mandibular structures in several early branching ‘acanthodian’-grade stem-chondrichthyans. We show that the dentigerous jaw bones of disparate genera of ischnacanthids are united by a common construction, being growing bones with non-shedding dentition. Mandibular splints, which support the ventro-lateral edge of the Meckel's cartilage in some taxa, are formed from dermal bone and may be an acanthodid synapomorphy. We demonstrate that the teeth of Acanthodopsis are borne directly on the mandibular cartilage and that this taxon is deeply nested within an edentulous radiation, representing an unexpected independent origin of teeth. Many or even all of the range of unusual oral structures may be apomorphic, but they should nonetheless be considered when building hypotheses of tooth and jaw evolution, both in chondrichthyans and more broadly.


2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Hong Zhang ◽  
Xiaopeng Zhao ◽  
Zhiguang Zhang ◽  
Weiwei Chen ◽  
Xinli Zhang

The purpose of this study is to investigate the spacial expression pattern and functional significance of three key transcription factors related to bone and cartilage formation, namely, Sox9, Runx2, and Osterix in cartilages during the late development of mouse mandible. Immunohistochemical examinations of Sox9, Runx2, and Osterix were conducted in the mandibular cartilages of the 15 neonatal C57BL/6N mice. In secondary cartilages, both Sox9 and Runx2 were weakly expressed in the polymorphic cell zone, strongly expressed in the flattened cell zone and throughout the entire hypertrophic cell zone. Similarly, both transcriptional factors were weakly expressed in the uncalcified Meckel’s cartilage while strongly expressed in the rostral cartilage. Meanwhile, Osterix was at an extremely low level in cells of the flattened cell zone and the upper hypertrophic cell zone in secondary cartilages. Surprisingly, Osterix was intensely expressed in hypertrophic chondrocytes in the center of the uncalcified Meckel’s cartilage while moderately expressed in part of hypertrophic chondrocytes in the rostral process. Consequently, it is suggested that Sox9 is a main and unique positive regulator in the hypertrophic differentiation process of mandibular secondary cartilages, in addition to Runx2. Furthermore, Osterix is likely responsible for phenotypic conversion of Meckel’s chondrocytes during its degeneration.


Development ◽  
1997 ◽  
Vol 124 (8) ◽  
pp. 1519-1530 ◽  
Author(s):  
J.R. Chin ◽  
Z. Werb

We have investigated the role of proteinases in the developmental program of bone, cartilage, tongue muscle and epithelial differentiation and remodeling in the mandibular arch during murine embryogenesis. Expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) was tissue-specific with little or no expression in the epithelium of tooth buds, tongue or oral cavity. Gelatinase A mRNA transcripts were strongly expressed in the perichondrium of Meckel's cartilage and mesenchymal areas of embryonic day 13–15 mandibles, whereas gelatinase B, collagenase-3, TIMP-1 and TIMP-2 mRNA were found primarily in the ossifying areas of the mandibles. The skeletal muscle of the tongue expressed stromelysin-3, TIMP-2 and TIMP-3 mRNA while stromelysin-3, TIMP-2 and gelatinase A were seen in the overlying connective tissue layer. Gelatinase A, gelatinase B, stromelysin-1, urokinase, TIMP-1 and TIMP-2 mRNA and protein activities were also detected in cultured mandibular explants. Culture of day 10 mandibular explants with a hydroxamic acid metalloproteinase inhibitor, but not with inhibitors of metalloendopeptidases (thiorphan and phosphoramidon), serine proteinases (aprotinin), cysteine proteinases (leupeptin) and urokinase (amiloride), altered mandibular morphogenesis dramatically. Development of the tongue (glossogenesis) and cartilage, but not bone or teeth was affected. Formation of the oral sulcus and fusion of the two epithelia of the medial sulcus were inhibited, and number and migration of myoblasts decreased. The resulting ‘tongue-tied phenotype’ indicates that MMPs are involved in epithelial morphogenesis and the migration of myoblasts to the region of the tongue. Development of the anterior segment of Meckel's cartilage was also inhibited and proteoglycan content of the cartilage was reduced by inhibiting MMPs. Our data suggest that matrix metalloproteinases play a pivotal role in the morphogenesis of structures derived from epithelium (oral sulcus), cranial paraxial mesoderm (tongue) and cranial neural crest (Meckel's cartilage).


Cells ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 131
Author(s):  
Federica Boraldi ◽  
Francesco Demetrio Lofaro ◽  
Daniela Quaglino

Extraosseous calcification is a pathologic mineralization process occurring in soft connective tissues (e.g., skin, vessels, tendons, and cartilage). It can take place on a genetic basis or as a consequence of acquired chronic diseases. In this last case, the etiology is multifactorial, including both extra- and intracellular mechanisms, such as the formation of membrane vesicles (e.g., matrix vesicles and apoptotic bodies), mitochondrial alterations, and oxidative stress. This review is an overview of extraosseous calcification mechanisms focusing on the relationships between apoptosis and mineralization in cartilage and vascular tissues, as these are the two tissues mostly affected by a number of age-related diseases having a progressively increased impact in Western Countries.


1995 ◽  
Vol 170 (2) ◽  
pp. 387-396 ◽  
Author(s):  
Kun Sung Chung ◽  
Howard H. Park ◽  
Kang Ting ◽  
Hiroko Takita ◽  
Suneel S. Apte ◽  
...  

2011 ◽  
Vol 218 (5) ◽  
pp. 517-533 ◽  
Author(s):  
Tamaki Yokohama-Tamaki ◽  
Takashi Maeda ◽  
Tetsuya S. Tanaka ◽  
Shunichi Shibata

2020 ◽  
pp. 002203452096011
Author(s):  
M. Farahat ◽  
G.A.S. Kazi ◽  
E.S. Hara ◽  
T. Matsumoto

During orofacial tissue development, the anterior and posterior regions of the Meckel’s cartilage undergo mineralization, while the middle region undergoes degeneration. Despite the interesting and particular phenomena, the mechanisms that regulate the different fates of Meckel’s cartilage, including the effects of biomechanical cues, are still unclear. Therefore, the purpose of this study was to systematically investigate the course of Meckel’s cartilage during embryonic development from a biomechanical perspective. Histomorphological and biomechanical (stiffness) changes in the Meckel’s cartilage were analyzed from embryonic day 12 to postnatal day 0. The results revealed remarkable changes in the morphology and size of chondrocytes, as well as the occurrence of chondrocyte burst in the vicinity of the mineralization site, an often-seen phenomenon preceding endochondral ossification. To understand the effect of biomechanical cues on Meckel’s cartilage fate, a mechanically tuned 3-dimensional hydrogel culture system was used. At the anterior region, a moderately soft environment (10-kPa hydrogel) promoted chondrocyte burst and ossification. On the contrary, at the middle region, a more rigid environment (40-kPa hydrogel) enhanced cartilage degradation by inducing a higher expression of MMP-1 and MMP-13. These results indicate that differences in the biomechanical properties of the surrounding environment are essential factors that distinctly guide the mineralization and degradation of Meckel’s cartilage and would be valuable tools for modulating in vitro cartilage and bone tissue engineering.


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