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The Medical versus Zoological Concept of Outflow Tract Valves of the Vertebrate Heart. J Cardiovasc Dev Dis 2022; 9:jcdd9100318. [PMID: 36286270 PMCID: PMC9604109 DOI: 10.3390/jcdd9100318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 09/15/2022] [Accepted: 09/20/2022] [Indexed: 11/17/2022] Open
Abstract
The anatomical elements that in humans prevent blood backflow from the aorta and pulmonary artery to the left and right ventriclesare the aortic and pulmonary valves, respectively. Each valve regularly consists of three leaflets (cusps), each supported by its valvular sinus. From the medical viewpoint, each set of three leaflets and sinuses is regarded as a morpho-functional unit. This notion also applies to birds and non-human mammals. However, the structures that prevent the return of blood to the heart in other vertebrates are notably different. This has led to discrepancies between physicians and zoologists in defining what a cardiac outflow tract valve is. The aim here is to compare the gross anatomy of the outflow tract valvular system among several groups of vertebrates in order to understand the conceptual and nomenclature controversies in the field.
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2
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Starck JM, Wyneken J. Comparative and Functional Anatomy of the Ectothermic Sauropsid Heart. Vet Clin North Am Exot Anim Pract 2022; 25:337-366. [PMID: 35422257 DOI: 10.1016/j.cvex.2022.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The heart development, form, and functional specializations of chelonians, squamates, crocodilians, and birds characterize how diverse structure and specializations arise from similar foundations. This review aims to summarize the morphologic diversity of sauropsid hearts and present it in an integrative functional and phylogenetic context. Besides the detailed morphologic descriptions, the integrative view of function, evolution, and development will aid understanding of the surprising diversity of sauropsid hearts. This integrated perspective is a foundation that strengthens appreciation that the sauropsid hearts are the outcome of biological evolution; disease often is linked to arising mismatch between adaptations and modern environments.
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Affiliation(s)
- J Matthias Starck
- Department of Biology, Ludwig-Maximilians-University Munich, Planegg-Martinsried D82152, Germany.
| | - Jeanette Wyneken
- Florida Atlantic University, FAU Marine Lab at Gumbo Limbo Environmental Complex, Boca Raton, FL 33431-0991, USA
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3
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Cieri RL, Turner ML, Carney RM, Falkingham PL, Kirk AM, Wang T, Jensen B, Novotny J, Tveite J, Gatesy SM, Laidlaw DH, Kaplan H, Moorman AFM, Howell M, Engel B, Cruz C, Smith A, Gerichs W, Lian Y, Schultz JT, Farmer CG. Virtual and augmented reality: New tools for visualizing, analyzing, and communicating complex morphology. J Morphol 2021; 282:1785-1800. [PMID: 34689352 DOI: 10.1002/jmor.21421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/30/2021] [Accepted: 10/10/2021] [Indexed: 11/09/2022]
Abstract
Virtual and augmented reality (VR/AR) are new technologies with the power to revolutionize the study of morphology. Modern imaging approaches such as computed tomography, laser scanning, and photogrammetry have opened up a new digital world, enabling researchers to share and analyze morphological data electronically and in great detail. Because this digital data exists on a computer screen, however, it can remain difficult to understand and unintuitive to interact with. VR/AR technologies bridge the analog-to-digital divide by presenting 3D data to users in a very similar way to how they would interact with actual anatomy, while also providing a more immersive experience and greater possibilities for exploration. This manuscript describes VR/AR hardware, software, and techniques, and is designed to give practicing morphologists and educators a primer on using these technologies in their research, pedagogy, and communication to a wide variety of audiences. We also include a series of case studies from the presentations and workshop given at the 2019 International Congress of Vertebrate Morphology, and suggest best practices for the use of VR/AR in comparative morphology.
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Affiliation(s)
- Robert L Cieri
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA.,School of Science and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Morgan L Turner
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA.,Department of Computer Science and Engineering, University of Minnesota, Minneapolis, Minnesota, USA
| | - Ryan M Carney
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Peter L Falkingham
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| | - Alexander M Kirk
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Tobias Wang
- Department of Biology, Zoophysiology, Aarhus University, Aarhus, Denmark
| | - Bjarke Jensen
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centres, Amsterdam, the Netherlands
| | - Johannes Novotny
- VRVis Zentrum für Virtual Reality und Visualisierung Forschungs-GmbH, Vienna, Austria
| | - Joshua Tveite
- Department of Computer Science, Brown University, Providence, Rhode Island, USA
| | - Stephen M Gatesy
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
| | - David H Laidlaw
- Department of Computer Science, Brown University, Providence, Rhode Island, USA
| | - Howard Kaplan
- Advanced Visualization Center, University of South Florida, Tampa, Florida, USA
| | - Antoon F M Moorman
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centres, Amsterdam, the Netherlands
| | - Mark Howell
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Benjamin Engel
- School of Dentistry, University of Utah, Salt Lake City, Utah, USA
| | - Cole Cruz
- School of Computing, University of Utah, Salt Lake City, Utah, USA
| | - Adam Smith
- School of Computing, University of Utah, Salt Lake City, Utah, USA
| | - William Gerichs
- School of Computing, University of Utah, Salt Lake City, Utah, USA
| | - Yingjie Lian
- School of Computing, University of Utah, Salt Lake City, Utah, USA
| | - Johanna T Schultz
- School of Science and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - C G Farmer
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
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Jensen B. Commemoration of Comparative Cardiac Anatomy of the Reptilia I-IV. J Morphol 2019; 280:623-626. [PMID: 30741427 PMCID: PMC6594047 DOI: 10.1002/jmor.20964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 01/28/2019] [Accepted: 02/01/2019] [Indexed: 12/13/2022]
Abstract
Our understanding of the anatomy of hearts of ectothermic saurosids, or colloquially “reptiles”, was much advanced by the publication of the series of four papers under the heading of Comparative Cardiac Anatomy of the Reptilia in Journal of Morphology between 1971 and 1981. Here, I commemorate the papers, show how they moved our understanding forwards, and briefly describe the state‐of‐the‐art.
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Affiliation(s)
- Bjarke Jensen
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, Amsterdam, The Netherlands
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Kvasilova A, Gregorovicova M, Kundrat M, Sedmera D. HNK‐1 in Morphological Study of Development of the Cardiac Conduction System in Selected Groups of Sauropsida. Anat Rec (Hoboken) 2018; 302:69-82. [DOI: 10.1002/ar.23925] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 05/31/2018] [Accepted: 06/11/2018] [Indexed: 01/14/2023]
Affiliation(s)
- Alena Kvasilova
- Institute of Anatomy, Charles University Prague Czech Republic
| | - Martina Gregorovicova
- Institute of Anatomy, Charles University Prague Czech Republic
- Institute of Physiology, The Czech Academy of Sciences Prague Czech Republic
| | - Martin Kundrat
- Center for Interdisciplinary Biosciences, Innovation and Technology Park, University of Pavol Jozef Safarik Kosice Slovak Republic
| | - David Sedmera
- Institute of Anatomy, Charles University Prague Czech Republic
- Institute of Physiology, The Czech Academy of Sciences Prague Czech Republic
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Keen AN, Shiels HA, Crossley DA. Cardiovascular function, compliance, and connective tissue remodeling in the turtle, Trachemys scripta, following thermal acclimation. Am J Physiol Regul Integr Comp Physiol 2016; 311:R133-43. [PMID: 27101300 PMCID: PMC4967230 DOI: 10.1152/ajpregu.00510.2015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 04/07/2016] [Indexed: 01/12/2023]
Abstract
Low temperature directly alters cardiovascular physiology in freshwater turtles, causing bradycardia, arterial hypotension, and a reduction in systemic blood pressure. At the same time, blood viscosity and systemic resistance increase, as does sensitivity to cardiac preload (e.g., via the Frank-Starling response). However, the long-term effects of these seasonal responses on the cardiovascular system are unclear. We acclimated red-eared slider turtles to a control temperature (25°C) or to chronic cold (5°C). To differentiate the direct effects of temperature from a cold-induced remodeling response, all measurements were conducted at the control temperature (25°C). In anesthetized turtles, cold acclimation reduced systemic resistance by 1.8-fold and increased systemic blood flow by 1.4-fold, resulting in a 2.3-fold higher right to left (R-L; net systemic) cardiac shunt flow and a 1.8-fold greater shunt fraction. Following a volume load by bolus injection of saline (calculated to increase stroke volume by 5-fold, ∼2.2% of total blood volume), systemic resistance was reduced while pulmonary blood flow and systemic pressure increased. An increased systemic blood flow meant the R-L cardiac shunt was further pronounced. In the isolated ventricle, passive stiffness was increased following cold acclimation with 4.2-fold greater collagen deposition in the myocardium. Histological sections of the major outflow arteries revealed a 1.4-fold higher elastin content in cold-acclimated animals. These results suggest that cold acclimation alters cardiac shunting patterns with an increased R-L shunt flow, achieved through reducing systemic resistance and increasing systemic blood flow. Furthermore, our data suggests that cold-induced cardiac remodeling may reduce the stress of high cardiac preload by increasing compliance of the vasculature and decreasing compliance of the ventricle. Together, these responses could compensate for reduced systolic function at low temperatures in the slider turtle.
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Affiliation(s)
- Adam N Keen
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom; and
| | - Holly A Shiels
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom; and
| | - Dane A Crossley
- Department of Biological Sciences, University of North Texas, Denton, Texas
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7
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Jensen B, Moorman AFM, Wang T. Structure and function of the hearts of lizards and snakes. Biol Rev Camb Philos Soc 2013; 89:302-36. [DOI: 10.1111/brv.12056] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 06/26/2013] [Accepted: 07/30/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Bjarke Jensen
- Department of Bioscience, Zoophysiology; Aarhus University; Aarhus C 8000 Denmark
- Department of Anatomy, Embryology & Physiology, Academic Medical Center; University of Amsterdam; Amsterdam 1105 The Netherlands
| | - Antoon F. M. Moorman
- Department of Anatomy, Embryology & Physiology, Academic Medical Center; University of Amsterdam; Amsterdam 1105 The Netherlands
| | - Tobias Wang
- Department of Bioscience, Zoophysiology; Aarhus University; Aarhus C 8000 Denmark
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Jensen B, van den Berg G, van den Doel R, Oostra RJ, Wang T, Moorman AFM. Development of the hearts of lizards and snakes and perspectives to cardiac evolution. PLoS One 2013; 8:e63651. [PMID: 23755108 PMCID: PMC3673951 DOI: 10.1371/journal.pone.0063651] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 04/04/2013] [Indexed: 12/16/2022] Open
Abstract
Birds and mammals both developed high performance hearts from a heart that must have been reptile-like and the hearts of extant reptiles have an unmatched variability in design. Yet, studies on cardiac development in reptiles are largely old and further studies are much needed as reptiles are starting to become used in molecular studies. We studied the growth of cardiac compartments and changes in morphology principally in the model organism corn snake (Pantherophis guttatus), but also in the genotyped anole (Anolis carolinenis and A. sagrei) and the Philippine sailfin lizard (Hydrosaurus pustulatus). Structures and chambers of the formed heart were traced back in development and annotated in interactive 3D pdfs. In the corn snake, we found that the ventricle and atria grow exponentially, whereas the myocardial volumes of the atrioventricular canal and the muscular outflow tract are stable. Ventricular development occurs, as in other amniotes, by an early growth at the outer curvature and later, and in parallel, by incorporation of the muscular outflow tract. With the exception of the late completion of the atrial septum, the adult design of the squamate heart is essentially reached halfway through development. This design strongly resembles the developing hearts of human, mouse and chicken around the time of initial ventricular septation. Subsequent to this stage, and in contrast to the squamates, hearts of endothermic vertebrates completely septate their ventricles, develop an insulating atrioventricular plane, shift and expand their atrioventricular canal toward the right and incorporate the systemic and pulmonary venous myocardium into the atria.
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Affiliation(s)
- Bjarke Jensen
- Department of Bioscience-Zoophysiology, Aarhus University, Aarhus, Denmark.
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Jensen B, Abe AS, Andrade DV, Nyengaard JR, Wang T. The heart of the South American rattlesnake, Crotalus durissus. J Morphol 2010; 271:1066-77. [DOI: 10.1002/jmor.10854] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Jensen B, Nyengaard JR, Pedersen M, Wang T. Anatomy of the python heart. Anat Sci Int 2010; 85:194-203. [PMID: 20376590 DOI: 10.1007/s12565-010-0079-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 03/09/2010] [Indexed: 10/19/2022]
Abstract
The hearts of all snakes and lizards consist of two atria and a single incompletely divided ventricle. In general, the squamate ventricle is subdivided into three chambers: cavum arteriosum (left), cavum venosum (medial) and cavum pulmonale (right). Although a similar division also applies to the heart of pythons, this family of snakes is unique amongst snakes in having intracardiac pressure separation. Here we provide a detailed anatomical description of the cardiac structures that confer this functional division. We measured the masses and volumes of the ventricular chambers, and we describe the gross morphology based on dissections of the heart from 13 ball pythons (Python regius) and one Burmese python (P. molurus). The cavum venosum is much reduced in pythons and constitutes approximately 10% of the cavum arteriosum. We suggest that shunts will always be less than 20%, while other studies conclude up to 50%. The high-pressure cavum arteriosum accounted for approximately 75% of the total ventricular mass, and was twice as dense as the low-pressure cavum pulmonale. The reptile ventricle has a core of spongious myocardium, but the three ventricular septa that separate the pulmonary and systemic chambers--the muscular ridge, the bulbuslamelle and the vertical septum--all had layers of compact myocardium. Pythons, however, have unique pads of connective tissue on the site of pressure separation. Because the hearts of varanid lizards, which also are endowed with pressure separation, share many of these morphological specializations, we propose that intraventricular compact myocardium is an indicator of high-pressure systems and possibly pressure separation.
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Affiliation(s)
- Bjarke Jensen
- Zoophysiology, Department of Biological Sciences, Aarhus University, Building 1131, 130, Universitetsparken, 8000 Århus C, Denmark.
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Starck JM. Functional morphology and patterns of blood flow in the heart of Python regius. J Morphol 2009; 270:673-87. [PMID: 19097161 DOI: 10.1002/jmor.10706] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Brightness-modulated ultrasonography, continuous-wave Doppler, and pulsed-wave Doppler-echocardiography were used to analyze the functional morphology of the undisturbed heart of ball pythons. In particular, the action of the muscular ridge and the atrio-ventricular valves are key features to understand how patterns of blood flow emerge from structures directing blood into the various chambers of the heart. A step-by-step image analysis of echocardiographs shows that during ventricular diastole, the atrio-ventricular valves block the interventricular canals so that blood from the right atrium first fills the cavum venosum, and blood from the left atrium fills the cavum arteriosum. During diastole, blood from the cavum venosum crosses the muscular ridge into the cavum pulmonale. During middle to late systole the muscular ridge closes, thus prohibiting further blood flow into the cavum pulmonale. At the same time, the atrio-ventricular valves open the interventricular canal and allow blood from the cavum arteriosum to flow into the cavum venosum. In the late phase of ventricular systole, all blood from the cavum pulmonale is pressed into the pulmonary trunk; all blood from the cavum venosum is pressed into both aortas. Quantitative measures of blood flow volume showed that resting snakes bypass the pulmonary circulation and shunt about twice the blood volume into the systemic circulation as into the pulmonary circulation. When digesting, the oxygen demand of snakes increased tremendously. This is associated with shunting more blood into the pulmonary circulation. The results of this study allow the presentation of a detailed functional model of the python heart. They are also the basis for a functional hypothesis of how shunting is achieved. Further, it was shown that shunting is an active regulation process in response to changing demands of the organism (here, oxygen demand). Finally, the results of this study support earlier reports about a dual pressure circulation in Python regius.
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Affiliation(s)
- J Matthias Starck
- Department of Biology II, Biocenter Martinsried, University of Munich (LMU), Planegg-Martinsried, Germany.
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Abstract
Major differences among reptile taxa include the shape of the heart, degree of separation of the ventricular compartments, degree of development of the intraventricular muscular ridge, and in crocodilians, the interventricular septum. In many cases, the structural-functional features of the reptilian heart provide adaptive plasticity, allowing for the ecological and behavioral diversity seen. As a result, variation may surface in clinical measures of cardiac performance. This article updates clinical context, provides an understanding of the variation in reptilian cardiovascular systems, and their functional implications for the assessment and treatment of reptile patients.
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Affiliation(s)
- Jeanette Wyneken
- Department of Biological Sciences, 266 Building 01, Sanson Science, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991, USA.
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Durán AC, López D, Guerrero A, Mendoza A, Arqué JM, Sans-Coma V. Formation of cartilaginous foci in the central fibrous body of the heart in Syrian hamsters (Mesocricetus auratus). J Anat 2004; 205:219-27. [PMID: 15379927 PMCID: PMC1571337 DOI: 10.1111/j.0021-8782.2004.00326.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2004] [Indexed: 11/30/2022] Open
Abstract
The formation of cartilage in the mammalian heart has been studied in the aortic and pulmonary valves. The chondrogenetic process that takes place in the cardiac skeleton is still unknown. The present study was designed to illustrate the ontogeny of cartilaginous foci occurring in the central fibrous body of the Syrian hamster (Mesocricetus auratus) heart. Hearts from 472 animals aged 0-708 days were examined using histological, histochemical and immunohistochemical techniques. Cartilage was present in the central fibrous body of 118 (25%) specimens. A further 104 hamsters were used for the detection of calcific deposits in the central fibrous body. Six (5.8%) showed calcified cartilage. The first sign related to chondrogenesis was the presence of small groups of cells embedded in a type II collagen-positive extracellular matrix. These cellular groups, which can appear as early as 2 days after birth, differentiate into hyaline cartilage or, less frequently, into fibrocartilage. The highest production of cartilaginous foci takes place between days 40 and 80. Thereafter, formation of new foci is uncommon. This indicates that appearance of cartilage in the central fibrous body of the heart is not a consequence of cardiac aging. The cartilaginous foci seem to act as pivots resisting mechanical tensions generated during the cardiac cycle. Deposition of calcium in the extracellular matrix of the foci can be regarded as a reinforcement of the cartilaginous tissue.
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Affiliation(s)
- A C Durán
- Department of Animal Biology, Faculty of Science, University of Málaga, Spain.
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López D, Durán AC, de Andrés AV, Guerrero A, Blasco M, Sans-Coma V. Formation of cartilage in the heart of the Spanish terrapin, Mauremys leprosa (Reptilia, Chelonia). J Morphol 2003; 258:97-105. [PMID: 12905537 DOI: 10.1002/jmor.10134] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cartilaginous deposits are regularly present in the heart of several reptilian, avian, and mammalian species. The formation of these extraskeletal cartilages has been studied in birds and mammals, but not in reptiles. The aim here was to elucidate this question in the Spanish terrapin. Hearts from 23 embryos belonging to Yntema (1968) developmental stages 17 to 26 and eight terrapins age 3 months to 10 years were examined using histological, histochemical, and immunohistochemical techniques. In the heart of the Spanish terrapin (Mauremys leprosa), chondrogenesis can start during embryonic life. Cartilaginous tissue develops from a mesenchymal cellular condensation that extends along the aorticopulmonary septum and the incipient pars fibrosa of the ventricular horizontal septum. This cellular condensation, which is smooth muscle alpha-actin (SMalpha-actin)-negative and type II collagen-negative during stages 17 to 22, acts as a prechondrogenic condensation. In stage 23, production of type II collagen begins in the central core of the condensation and gradually spreads toward its periphery. The type II collagen-positive (chondrogenic) cellular condensation remains devoid of perichondrium prior to birth. Thereafter, it converts into hyaline cartilage that extends along the proximal part of the aorticopulmonary septum and the pars fibrosa of the horizontal septum. Our findings are consistent with the assumption that, as in birds and mammals, the precursors of the cardiac chondrocytes in chelonians are neural crest-derived cells of nonmuscular nature. In addition, they point to the possibility that cells from the neural crest populate the embryonic pars fibrosa of the horizontal septum, thereby contributing to its alignment with the aorticopulmonary septum. In the present species, a second cartilaginous deposit of a hyaline nature extends along the sinus wall of the right semilunar valve of the right aorta, penetrating the fibrous cushion that constitutes the proximal support of the corresponding valve leaflet. This cartilage develops after birth, between the third and eighteenth month of life; its morphogenetic origin is unclear. The cartilaginous foci occurring in hearts of Spanish terrapin appear to act as pivots resisting mechanical tensions generated during the cardiac cycle. In the specimens examined there was no sign of replacement of the cardiac cartilages by bone tissue.
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Affiliation(s)
- David López
- Department of Animal Biology, Faculty of Science, University of Málaga, 29071 Málaga, Spain
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Mechanisms of Intracardiac Shunting in Reptiles: Pressure vs Washout Shunting. ACTA ACUST UNITED AC 1995. [DOI: 10.1007/978-3-642-79666-1_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
BACKGROUND The cartilago cordis, a cartilaginous element present within the heart, has been found in a number of vertebrates. The present study provides a detailed description and comparative analysis of the cartilago cordis in snakes. METHODS Transverse sections through the hearts of 42 snakes and three monitor lizards were examined. RESULTS A cartilago cordis was found near the roots of the aortic trunk and pulmonary artery in eleven species of snakes. There is substantial variation in the size, shape, and precise location of the cartilago cordis. CONCLUSIONS The presence of a cartilago cordis does not correlate with body size, taxonomic relationships, or habitat preference. The cartilago cordis may simply represent an illustration of the potential for chondrification that is present in the connective tissue of the aorticopulmonary septum.
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Affiliation(s)
- B A Young
- Department of Biology, Hollins College, Roanoke, Virginia 24020
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Young BA, Lillywhite HB, Wassersug RJ. On the structure of the aortic valves in snakes (Reptilia: Serpentes). J Morphol 1993; 216:141-159. [DOI: 10.1002/jmor.1052160204] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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MacKinnon MR, Heatwole H. Comparative cardiac anatomy of the reptilia. IV. The coronary arterial circulation. J Morphol 1981; 170:1-27. [PMID: 7288884 DOI: 10.1002/jmor.1051700102] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The coronary arterial supply and associated structures have been examined and described for 29 species covering 11 reptilian families, with supplementary observations on other species. Variation in the origin, number, and configuration of coronary arterial vessels is mainly interfamilial and the same is true regarding the presence or absence of a gubernaculum cordis. It is suggested that the presence of a hitherto unrecognized intertruncal branch of the coronary artery has been responsible for much of the alleged intrafamilial variation reported in earlier literature. A general review of the cardiac blood supply and coronary arterial supply of other lower vertebrates is presented and used as a basis for interpreting phyletic and functional aspects of the reptilian conditions.
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Webb GJW. Comparative cardiac anatomy of the reptilia. III. The heart of crocodilians and an hypothesis on the completion of the interventricular septum of crocodilians and birds. J Morphol 1979; 161:221-240. [DOI: 10.1002/jmor.1051610209] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
After dissecting a variety of vertebrate hearts and extensively reviewing the literature, I have drawn some conclusions concerning the phylogeny of the tetrapod heart that differ from commonly expressed viewpoints in the literature. It is probable that the absence of an interventricular septum in amphibians is a primitive feature (rather than representing a loss). The complete interventricular septum of crocodilians and birds probably evolved primarily from the major horizontal septum of the typical (noncrocodilian) reptilian heart, with a smaller part representing a new development. The interventricular septum of mammals probably also evolved primarily from the reptilian horizontal septum. There is no reason to assume that the mammalian heart and aortic arches evolved directly from a pre-reptilian stage, as is often assumed. The evidence upon which these conclusions are based is given.
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Affiliation(s)
- E Bruce Holmes
- Department of Biological Sciences, Western Illinois University, Macomb, Illinois 61455
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