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Weronika Rupik - One of the best experts on this subject based on the ideXlab platform.
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Ultrastructural studies of developing egg tooth in Grass Snake Natrix natrix (Squamata, Serpentes) embryos, supported by X-ray microtomography analysis
Zoology (Jena Germany), 2021Co-Authors: Mateusz Hermyt, Brian D. Metscher, Weronika RupikAbstract:Abstract The egg tooth development is similar to the development of all the other vertebrate teeth except earliest developmental stages because the egg tooth develops directly from the oral epithelium instead of the dental lamina similarly to null generation teeth. The developing egg tooth of Natrix natrix changes its curvature differently than the egg tooth of the other investigated unidentates due to the presence of the rostral groove. The developing Grass Snake egg tooth comprises dental pulp and the enamel organ. The fully differentiated enamel organ consists of outer enamel epithelium, stellate reticulum, and ameloblasts in its inner layer. The enamel organ directly in contact with the oral cavity is covered with periderm instead of outer enamel epithelium. Stellate reticulum cells in the Grass Snake egg tooth share intercellular spaces with the basal part of ameloblasts and are responsible for their nutrition. Ameloblasts during egg tooth differentiation pass through the following stages: presecretory, secretory, and mature. The ameloblasts from the Grass Snake egg tooth show the same cellular changes as reported during mammalian amelogenesis but are devoid of Tomes’ processes. Odontoblasts of the developing Grass Snake egg tooth pass through the following classes: pre-odontoblasts, secretory odontoblasts, and ageing odontoblasts. They have highly differentiated secretory apparatus and in the course of their activity accumulate lipofuscin. Grass Snake odontoblasts possess processes which are poor in organelles. In developing egg tooth cilia have been identified in odontoblasts, ameloblasts and cells of the stellate reticulum. Dental pulp cells remodel collagen matrix during growth of the Grass Snake egg tooth. They degenerate in a way previously not described in other teeth.
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structural and ultrastructural studies on the developing vomeronasal sensory epithelium in the Grass Snake natrix natrix squamata colubroidea
Journal of Morphology, 2021Co-Authors: Pawel Kaczmarek, Weronika RupikAbstract:The sensory olfactory epithelium and the vomeronasal sensory epithelium (VSE) are characterized by continuous turnover of the receptor cells during postnatal life and are capable of regeneration after injury. The VSE, like the entire vomeronasal organ, is generally well developed in squamates and is crucial for detection of pheromones and prey odors. Despite the numerous studies on embryonic development of the VSE in squamates, especially in Snakes, an ultrastructural analysis, as far as we know, has never been performed. Therefore, we investigated the embryology of the VSE of the Grass Snake (Natrix natrix) using electron microscopy (SEM and TEM) and light microscopy. As was shown for adult Snakes, the hypertrophied ophidian VSE may provide great resolution of changes in neuron morphology located at various epithelial levels. The results of this study suggest that different populations of stem/progenitor cells occur at the base of the ophidian VSE during embryonic development. One of them may be radial glia-like cells, described previously in mouse. The various structure and ultrastructure of neurons located at different parts of the VSE provide evidence for neuronal maturation and aging. Based on these results, a few nonmutually exclusive hypotheses explaining the formation of the peculiar columnar organization of the VSE in Snakes were proposed.
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Development of pancreatic acini in embryos of the Grass Snake Natrix natrix (Lepidosauria, Serpentes)
Journal of morphology, 2019Co-Authors: Magdalena Kowalska, Weronika RupikAbstract:This study report about the differentiation of pancreatic acinar tissue in Grass Snake, Natrix natrix, embryos using light microscopy, transmission electron microscopy, and immuno-gold labeling. Differentiation of acinar cells in the embryonic pancreas of the Grass Snake is similar to that of other amniotes. Pancreatic acini occurred for the first time at Stage VIII, which is the midpoint of embryonic development. Two pattern of acinar cell differentiation were observed. The first involved formation of zymogen granules followed by cell migration from ducts. In the second, one zymogen granule was formed at the end of acinar cell differentiation. During embryonic development in the pancreatic acini of N. natrix, five types of zymogen granules were established, which correlated with the degree of their maturation and condensation. Within differentiating acini of the studied species, three types of cells were present: acinar, centroacinar, and endocrine cells. The origin of acinar cells as well as centroacinar cells in the pancreas of the studied species was the pancreatic ducts, which is similar as in other vertebrates. In the differentiating pancreatic acini of N. natrix, intermediate cells were not present. It may be related to the lack of transdifferentiation activity of acinar cells in the studied species. Amylase activity of exocrine pancreas was detected only at the end of embryonic development, which may be related to animal feeding after hatching from external sources that are rich in carbohydrates and presence of digestive enzymes in the egg yolk. Mitotic division of acinar cells was the main mechanism of expansion of acinar tissue during pancreas differentiation in the Grass Snake embryos.
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Development of endocrine pancreatic islets in embryos of the Grass Snake Natrix natrix (Lepidosauria, Serpentes).
Journal of morphology, 2018Co-Authors: Magdalena Kowalska, Weronika RupikAbstract:Differentiation of the pancreatic islets in Grass Snake Natrix natrix embryos, was analyzed using light, transmission electron microscopy, and immuno-gold labeling. The study focuses on the origin of islets, mode of islet formation, and cell arrangement within islets. Two waves of pancreatic islet formation in Grass Snake embryos were described. The first wave begins just after egg laying when precursors of endocrine cells located within large cell agglomerates in the dorsal pancreatic bud differentiate. The large cell agglomerates were divided by mesenchymal cells thus forming the first islets. This mode of islet formation is described as fission. During the second wave of pancreatic islet formation which is related to the formation of the duct mantle, we observed four phases of islet formation: (a) differentiation of individual endocrine cells from the progenitor layer of duct walls (budding) and their incomplete delamination; (b) formation of two types of small groups of endocrine cells (A/D and B) in the wall of pancreatic ducts; (c) joining groups of cells emerging from neighboring ducts (fusion) and rearrangement of cells within islets; (d) differentiated pancreatic islets with characteristic arrangement of endocrine cells. Mature pancreatic islets of the Grass Snake contained mainly A endocrine cells. Single B and D or PP-cells were present at the periphery of the islets. This arrangement of endocrine cells within pancreatic islets of the Grass Snake differs from that reported from most others vertebrate species. Endocrine cells in the pancreas of Grass Snake embryos were also present in the walls of intralobular and intercalated ducts. At hatching, some endocrine cells were in contact with the lumen of the pancreatic ducts.
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Ultrastructure of endocrine pancreatic granules during pancreatic differentiation in the Grass Snake, Natrix natrix L. (Lepidosauria, Serpentes).
Journal of morphology, 2017Co-Authors: Magdalena Kowalska, Weronika RupikAbstract:We used transmission electron microscopy to study the pancreatic main endocrine cell types in the embryos of the Grass Snake Natrix natrix L. with focus on the morphology of their secretory granules. The embryonic endocrine part of the pancreas in the Grass Snake contains four main types of cells (A, B, D, and PP), which is similar to other vertebrates. The B granules contained a moderately electron-dense crystalline-like core that was polygonal in shape and an electron-dense outer zone. The A granules had a spherical electron-dense eccentrically located core and a moderately electron-dense outer zone. The D granules were filled with a moderately electron-dense non-homogeneous content. The PP granules had a spherical electron-dense core with an electron translucent outer zone. Within the main types of granules (A, B, D, PP), different morphological subtypes were recognized that indicated their maturity, which may be related to the different content of these granules during the process of maturation. The sequence of pancreatic endocrine cell differentiation in Grass Snake embryos differs from that in many vertebrates. In the Grass Snake embryos, the B and D cells differentiated earlier than A and PP cells. The different sequence of endocrine cell differentiation in Snakes and other vertebrates has been related to phylogenetic position and nutrition during early developmental stages.
Uwe Fritz - One of the best experts on this subject based on the ideXlab platform.
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The valid scientific names of the barred Grass Snake and its subspecies from mainland Italy and Sicily
Amphibia-Reptilia, 2020Co-Authors: Uwe Fritz, Edoardo Razzetti, Josef Friedrich SchmidtlerAbstract:Abstract To stabilize current nomenclature, Coluber helveticus Lacepède, 1789 and Coluber siculus Cuvier, 1829 are qualified as nomina protecta to ensure the usage of the established names Natrix helvetica (Lacepède, 1789) and Natrix helvetica sicula (Cuvier, 1829) for the barred Grass Snake. For the same reason, Coluber bipes Gmelin, 1789, Coluber tyrolensis Gmelin, 1789 and Coluber scopolianus Daudin, 1803, all with type locality Dolomiti di Fiemme (Italy), are declared as nomina oblita according to Article 23.9 of the International Code of Zoological Nomenclature (1999). Coluber helveticus Lacepède, 1789 was originally introduced as a replacement name for Coluber vulgaris Razoumowsky, 1789 (type locality: Jorat, Switzerland). However, the latter name becomes a junior secondary homonym of Natrix vulgaris Laurenti, 1768 when transferred to the genus Natrix and thus, according to Articles 57 and 59 of the Code, invalid and does not threaten the usage of Natrix helvetica for the barred Grass Snake.
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Distribution and hybridisation of barred and common Grass Snakes (Natrix helvetica, N. natrix) in Baden-Württemberg, South-western Germany
Herpetozoa, 2019Co-Authors: Nadine Schultze, Carolin Kindler, Hubert Laufer, Uwe FritzAbstract:The distribution and hybridisation zone of the two Grass Snake species occurring in the German state of Baden-Württemberg are described, based on genetic data from maternally inherited mitochondrial DNA (mtDNA, up to 1983 bp) and biparentally inherited microsatellite DNA (13 loci). In agreement with previously published morphological evidence, the barred Grass Snake (Natrix helvetica) occurs in the Upper Rhine Valley and the Black Forest, while the common Grass Snake (N. natrix, ‘yellow lineage’) is distributed across the remaining, more eastern parts of Baden-Württemberg. Cline analyses across two transects running through the region of Karlsruhe and the Black Forest indicate that the hybrid zone is similarly narrow here as in the previously characterised stretch near Lake Constance. With respect to nuclear DNA, the Black Forest constitutes no impediment to gene flow in comparison with lowland regions (Karlsruhe, Lake Constance). However, on the eastern slope of the Black Forest, the abrupt replacement of mtDNA of N. helvetica by that of N. natrix indicates male-mediated gene flow and that the Black Forest represents a dispersal barrier for female Grass Snakes.
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Extra-Mediterranean glacial refuges in barred and common Grass Snakes (Natrix helvetica, N. natrix).
Scientific reports, 2018Co-Authors: Carolin Kindler, Eva Graciá, Uwe FritzAbstract:Extra-Mediterranean glacial refugia of thermophilic biota, in particular in northern latitudes, are controversial. In the present study we provide genetic evidence for extra-Mediterranean refugia in two species of Grass Snake. The refuge of a widely distributed western European lineage of the barred Grass Snake (Natrix helvetica) was most likely located in southern France, outside the classical refuges in the southern European peninsulas. One genetic lineage of the common Grass Snake (N. natrix), distributed in Scandinavia, Central Europe and the Balkan Peninsula, had two distinct glacial refuges. We show that one was located in the southern Balkan Peninsula. However, Central Europe and Scandinavia were not colonized from there, but from a second refuge in Central Europe. This refuge was located in between the northern ice sheet and the Alpine glaciers of the last glaciation and most likely in a permafrost region. Another co-distributed genetic lineage of N. natrix, now massively hybridizing with the aforementioned lineage, survived the last glaciation in a structured refuge in the southern Balkan Peninsula, according to the idea of ‘refugia-within-refugia’. It reached Central Europe only very recently. This study reports for the first time the glacial survival of a thermophilic egg-laying reptile species in Central Europe.
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Phylogeography of the Ibero-Maghrebian red-eyed Grass Snake ( Natrix astreptophora )
Organisms Diversity & Evolution, 2017Co-Authors: Carolin Kindler, Philip De Pous, Salvador Carranza, Menad Beddek, Philippe Geniez, Uwe FritzAbstract:We examined phylogeographic differentiation of the red-eyed Grass Snake (Natrix astreptophora) using 1984 bp of mtDNA and 13 microsatellite loci from specimens collected across its distribution range in southwestern Europe and northwestern Africa. Based on phylogenetic analyses of mtDNA, European N. astreptophora constituted the sister clade to a weakly supported North African clade comprised of two deeply divergent and well-supported clades, one corresponding to Moroccan Snakes and the other to Snakes from Algeria and Tunisia. This tripartite differentiation was confirmed by analyses of microsatellite loci. According to a fossil-calibrated molecular clock, European and North African N. astreptophora diverged 5.44 million years ago (mya), and the two Maghrebian clades split 4.64 mya. These dates suggest that the radiation of the three clades was initiated by the environmental changes related to the Messinian Salinity Crisis and the reflooding of the Mediterranean Basin. The differentiation of N. astreptophora, with distinct clades in the Iberian Peninsula and in the western and eastern Maghreb, corresponds to a general phylogeographic paradigm and resembles the differentiation found in another co-distributed Natrix species, the viperine Snake (N. maura). Despite both species being good swimmers, the Strait of Gibraltar constitutes a significant biogeographic barrier for them. The discovery that North Africa harbours two endemic lineages of N. astreptophora necessitates more conservation efforts for these imperilled Snakes.
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integrative taxonomy provides evidence for the species status of the ibero maghrebian Grass Snake natrix astreptophora
Biological Journal of The Linnean Society, 2016Co-Authors: Felix Pokrant, Carolin Kindler, Philippe Geniez, Martin Ivanov, Marc Cheylan, Wolfgang Böhme, Uwe FritzAbstract:The Grass Snake (Natrix natrix) is Europe's most widely distributed and, in many regions, most common Snake species, with many morphologically defined subspecies. Yet, the taxonomy of Grass Snakes is relatively little studied and recent work has shown major conflicts between morphologically defined subspecies and phylogeographical differentiation. Using external morphology, osteological characters, and information from 13 microsatellite loci and two mitochondrial markers, we examine differentiation of the subspecies N. n. astreptophora from the North African Maghreb region, the Iberian Peninsula and neighbouring France. According to previous studies, N. n. astreptophora corresponds to a deeply divergent mitochondrial clade and constitutes the sister taxon of all remaining Grass Snakes. In the French Pyrenees region, there is a contact zone of N. n. astreptophora with another subspecies, N. n. helvetica. Our analyses of microsatellites and mitochondrial DNA reveal that the distribution ranges of the two taxa abut there, but both hybridize only exceptionally. Even though many morphological characters are highly variable and homoplastic in Grass Snakes, N. n. astreptophora differs consistently from all other Grass Snakes by its reddish iris coloration and in having significantly fewer ventral scales and another skull morphology. Considering further the virtual absence of gene flow between N. n. astreptophora and N. n. helvetica, and acknowledging the morphological distinctiveness of N. n. astreptophora and its sister group relationship to all remaining subspecies of Grass Snakes, we conclude that Natrix astreptophora (Seoane, 1884) should be recognized as a distinct species. Further research is needed to explore whether N.astreptophora is polytypic because a single sample of N.astreptophora from Tunisia turned out to be genetically highly distinct from its European conspecifics.
Mateusz Hermyt - One of the best experts on this subject based on the ideXlab platform.
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Ultrastructural studies of developing egg tooth in Grass Snake Natrix natrix (Squamata, Serpentes) embryos, supported by X-ray microtomography analysis
Zoology (Jena Germany), 2021Co-Authors: Mateusz Hermyt, Brian D. Metscher, Weronika RupikAbstract:Abstract The egg tooth development is similar to the development of all the other vertebrate teeth except earliest developmental stages because the egg tooth develops directly from the oral epithelium instead of the dental lamina similarly to null generation teeth. The developing egg tooth of Natrix natrix changes its curvature differently than the egg tooth of the other investigated unidentates due to the presence of the rostral groove. The developing Grass Snake egg tooth comprises dental pulp and the enamel organ. The fully differentiated enamel organ consists of outer enamel epithelium, stellate reticulum, and ameloblasts in its inner layer. The enamel organ directly in contact with the oral cavity is covered with periderm instead of outer enamel epithelium. Stellate reticulum cells in the Grass Snake egg tooth share intercellular spaces with the basal part of ameloblasts and are responsible for their nutrition. Ameloblasts during egg tooth differentiation pass through the following stages: presecretory, secretory, and mature. The ameloblasts from the Grass Snake egg tooth show the same cellular changes as reported during mammalian amelogenesis but are devoid of Tomes’ processes. Odontoblasts of the developing Grass Snake egg tooth pass through the following classes: pre-odontoblasts, secretory odontoblasts, and ageing odontoblasts. They have highly differentiated secretory apparatus and in the course of their activity accumulate lipofuscin. Grass Snake odontoblasts possess processes which are poor in organelles. In developing egg tooth cilia have been identified in odontoblasts, ameloblasts and cells of the stellate reticulum. Dental pulp cells remodel collagen matrix during growth of the Grass Snake egg tooth. They degenerate in a way previously not described in other teeth.
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Embryology of the VNO and associated structures in the Grass Snake Natrix natrix (Squamata: Natricinae): a 3D perspective
Frontiers in Zoology, 2017Co-Authors: Paweł Kaczmarek, Mateusz Hermyt, Weronika RupikAbstract:Background Snakes are considered to be vomerolfaction specialists. They are members of one of the most diverse groups of vertebrates, Squamata. The vomeronasal organ and the associated structures (such as the lacrimal duct, choanal groove, lamina transversalis anterior and cupola Jacobsoni) of adult lizards and Snakes have received much anatomical, histological, physiological and behavioural attention. However, only limited embryological investigation into these structures, constrained to some anatomical or cellular studies and brief surveys, has been carried out thus far. The purpose of this study was, first, to examine the embryonic development of the vomeronasal organ and the associated structures in the Grass Snake ( Natrix natrix ), using three-dimensional reconstructions based on histological studies, and, second, to compare the obtained results with those presented in known publications on other Snakes and lizards. Results Five major developmental processes were taken into consideration in this study: separation of the vomeronasal organ from the nasal cavity and its specialization, development of the mushroom body, formation of the lacrimal duct, development of the cupola Jacobsoni and its relation to the vomeronasal nerve, and specialization of the sensory epithelium. Our visualizations showed the VNO in relation to the nasal cavity, choanal groove, lacrimal duct and cupola Jacobsoni at different embryonic stages. We confirmed that the choanal groove disappears gradually, which indicates that this structure is absent in adult Grass Snakes. On our histological sections, we observed a gradual growth in the height of the columns of the vomeronasal sensory epithelium and widening of the spaces between them. Conclusions The main ophidian taxa (Scolecophidia, Henophidia and Caenophidia), just like other squamate clades, seem to be evolutionarily conservative at some levels with respect to the VNO and associated structures morphology. Thus, it was possible to homologize certain embryonic levels of the anatomical and histological complexity, observed in the Grass Snake, with adult conditions of certain groups of Squamata. This may reflect evolutionary shift in Squamata from visually oriented predators to vomerolfaction specialists. Our descriptions offer material useful for future comparative studies of Squamata, both at their anatomical and histological levels.
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Embryology of the VNO and associated structures in the Grass Snake Natrix natrix (Squamata: Natricinae): a 3D perspective
Frontiers in zoology, 2017Co-Authors: Paweł Kaczmarek, Mateusz Hermyt, Weronika RupikAbstract:Background Snakes are considered to be vomerolfaction specialists. They are members of one of the most diverse groups of vertebrates, Squamata. The vomeronasal organ and the associated structures (such as the lacrimal duct, choanal groove, lamina transversalis anterior and cupola Jacobsoni) of adult lizards and Snakes have received much anatomical, histological, physiological and behavioural attention. However, only limited embryological investigation into these structures, constrained to some anatomical or cellular studies and brief surveys, has been carried out thus far. The purpose of this study was, first, to examine the embryonic development of the vomeronasal organ and the associated structures in the Grass Snake (Natrix natrix), using three-dimensional reconstructions based on histological studies, and, second, to compare the obtained results with those presented in known publications on other Snakes and lizards.
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Additional file 1: of Embryology of the VNO and associated structures in the Grass Snake Natrix natrix (Squamata: Naticinae): a 3D perspective
2017Co-Authors: Paweł Kaczmarek, Mateusz Hermyt, Weronika RupikAbstract:The transverse sections through the choanal region of the Grass Snake embryos at different developmental stages Abbreviations: AOR Antorbitalraum, CH choana, CHG choanal groove, DDNP dorsal communication of the nasopharyngeal ducts, DNP nasopharyngeal duct, FDNP fusion of the nasopharyngeal ducts, LD lacrimal duct, MPT medial palatal trough, OC oral cavity, T tongue. Scale bars 100 μm. (TIF 13612 kb
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Development of the egg tooth – The tool facilitating hatching of squamates: Lessons from the Grass Snake Natrix natrix
Zoologischer Anzeiger, 2017Co-Authors: Mateusz Hermyt, Magdalena Kowalska, Paweł Kaczmarek, Weronika RupikAbstract:Abstract Most embryos of squamates use their egg tooth to facilitate hatching when their development is completed. After they are out of the shell, this tooth is shed and, in the case, of the Grass Snake ( Natrix natrix ), not replaced by a successor teeth. The structure of this transient tooth resembles the development and histology of the regular teeth of vertebrates. Morphological, histological and scanning electron microscopic observations indicated that the egg tooth of the Grass Snake has four developmental phases. Like the teeth of other vertebrate species, it undergoes oral epithelium thickening as well as the bud, cap and bell phases. However, due to the specialised function it performs, the egg tooth differs significantly from the other teeth both in its morphology and development. The egg tooth of Natrix natrix embryos is an unpaired true tooth, as in most squamates. Our study indicated that the egg tooth started its development in the rostral part of the snout by the thickening of the oral epithelium and there was a condensation of mesenchyme underneath it. It formed very early, around developmental stage III, at approximately the same time as the null-generation teeth. After the thickening of the oral epithelium, only one tooth germ is formed, in contrast to lizards in which two germs can be observed during their embryonic life; however, in the course of development, one regressed and the other shifted into the midline position and developed into the functional egg tooth. The next step in the egg tooth development was the differentiation of the enamel organ and the dental papilla. Three layers of the enamel organ developed – the inner enamel epithelium, the stellate reticulum and the outer enamel epithelium, while a superficial layer of the dental papilla differentiated into the odontoblasts. The egg tooth was ready to erupt when its development ended at developmental stage XII, after the hard tissues developed.
Paweł Kaczmarek - One of the best experts on this subject based on the ideXlab platform.
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Embryology of the VNO and associated structures in the Grass Snake Natrix natrix (Squamata: Natricinae): a 3D perspective
Frontiers in Zoology, 2017Co-Authors: Paweł Kaczmarek, Mateusz Hermyt, Weronika RupikAbstract:Background Snakes are considered to be vomerolfaction specialists. They are members of one of the most diverse groups of vertebrates, Squamata. The vomeronasal organ and the associated structures (such as the lacrimal duct, choanal groove, lamina transversalis anterior and cupola Jacobsoni) of adult lizards and Snakes have received much anatomical, histological, physiological and behavioural attention. However, only limited embryological investigation into these structures, constrained to some anatomical or cellular studies and brief surveys, has been carried out thus far. The purpose of this study was, first, to examine the embryonic development of the vomeronasal organ and the associated structures in the Grass Snake ( Natrix natrix ), using three-dimensional reconstructions based on histological studies, and, second, to compare the obtained results with those presented in known publications on other Snakes and lizards. Results Five major developmental processes were taken into consideration in this study: separation of the vomeronasal organ from the nasal cavity and its specialization, development of the mushroom body, formation of the lacrimal duct, development of the cupola Jacobsoni and its relation to the vomeronasal nerve, and specialization of the sensory epithelium. Our visualizations showed the VNO in relation to the nasal cavity, choanal groove, lacrimal duct and cupola Jacobsoni at different embryonic stages. We confirmed that the choanal groove disappears gradually, which indicates that this structure is absent in adult Grass Snakes. On our histological sections, we observed a gradual growth in the height of the columns of the vomeronasal sensory epithelium and widening of the spaces between them. Conclusions The main ophidian taxa (Scolecophidia, Henophidia and Caenophidia), just like other squamate clades, seem to be evolutionarily conservative at some levels with respect to the VNO and associated structures morphology. Thus, it was possible to homologize certain embryonic levels of the anatomical and histological complexity, observed in the Grass Snake, with adult conditions of certain groups of Squamata. This may reflect evolutionary shift in Squamata from visually oriented predators to vomerolfaction specialists. Our descriptions offer material useful for future comparative studies of Squamata, both at their anatomical and histological levels.
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Embryology of the VNO and associated structures in the Grass Snake Natrix natrix (Squamata: Natricinae): a 3D perspective
Frontiers in zoology, 2017Co-Authors: Paweł Kaczmarek, Mateusz Hermyt, Weronika RupikAbstract:Background Snakes are considered to be vomerolfaction specialists. They are members of one of the most diverse groups of vertebrates, Squamata. The vomeronasal organ and the associated structures (such as the lacrimal duct, choanal groove, lamina transversalis anterior and cupola Jacobsoni) of adult lizards and Snakes have received much anatomical, histological, physiological and behavioural attention. However, only limited embryological investigation into these structures, constrained to some anatomical or cellular studies and brief surveys, has been carried out thus far. The purpose of this study was, first, to examine the embryonic development of the vomeronasal organ and the associated structures in the Grass Snake (Natrix natrix), using three-dimensional reconstructions based on histological studies, and, second, to compare the obtained results with those presented in known publications on other Snakes and lizards.
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Additional file 1: of Embryology of the VNO and associated structures in the Grass Snake Natrix natrix (Squamata: Naticinae): a 3D perspective
2017Co-Authors: Paweł Kaczmarek, Mateusz Hermyt, Weronika RupikAbstract:The transverse sections through the choanal region of the Grass Snake embryos at different developmental stages Abbreviations: AOR Antorbitalraum, CH choana, CHG choanal groove, DDNP dorsal communication of the nasopharyngeal ducts, DNP nasopharyngeal duct, FDNP fusion of the nasopharyngeal ducts, LD lacrimal duct, MPT medial palatal trough, OC oral cavity, T tongue. Scale bars 100 μm. (TIF 13612 kb
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Development of the egg tooth – The tool facilitating hatching of squamates: Lessons from the Grass Snake Natrix natrix
Zoologischer Anzeiger, 2017Co-Authors: Mateusz Hermyt, Magdalena Kowalska, Paweł Kaczmarek, Weronika RupikAbstract:Abstract Most embryos of squamates use their egg tooth to facilitate hatching when their development is completed. After they are out of the shell, this tooth is shed and, in the case, of the Grass Snake ( Natrix natrix ), not replaced by a successor teeth. The structure of this transient tooth resembles the development and histology of the regular teeth of vertebrates. Morphological, histological and scanning electron microscopic observations indicated that the egg tooth of the Grass Snake has four developmental phases. Like the teeth of other vertebrate species, it undergoes oral epithelium thickening as well as the bud, cap and bell phases. However, due to the specialised function it performs, the egg tooth differs significantly from the other teeth both in its morphology and development. The egg tooth of Natrix natrix embryos is an unpaired true tooth, as in most squamates. Our study indicated that the egg tooth started its development in the rostral part of the snout by the thickening of the oral epithelium and there was a condensation of mesenchyme underneath it. It formed very early, around developmental stage III, at approximately the same time as the null-generation teeth. After the thickening of the oral epithelium, only one tooth germ is formed, in contrast to lizards in which two germs can be observed during their embryonic life; however, in the course of development, one regressed and the other shifted into the midline position and developed into the functional egg tooth. The next step in the egg tooth development was the differentiation of the enamel organ and the dental papilla. Three layers of the enamel organ developed – the inner enamel epithelium, the stellate reticulum and the outer enamel epithelium, while a superficial layer of the dental papilla differentiated into the odontoblasts. The egg tooth was ready to erupt when its development ended at developmental stage XII, after the hard tissues developed.
Roger S. Thorpe - One of the best experts on this subject based on the ideXlab platform.
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Multivariate patterns of geographic variation between the island and mainland populations of the Eastern Grass Snake (Natrix natrix natrix)
Journal of Zoology, 2009Co-Authors: Roger S. ThorpeAbstract:The substantial racial variation between the mainland and island populations of the Eastern Grass Snake (Natrix natrix natrix) is analysed by a range of multivariate methods, including principal component and canonical analysis. These techniques reveal a complex pattern of geographic variation which include sharp transition zones, gradual clines, a wide range of divergence of island populations and greater divergence per distance in the south than in the north. These patterns relate to the phylogenesis of this “incipient” species, and its post-Pleistocene range expansion as presented here and elsewhere. These racial patterns do not generally relate to physiographic features, conventional subspecies or CURRENT physical or biotic factors.
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Geographic variation in the Western Grass Snake (Natrix natrix helvetica) in relation to hypothesized phylogeny and conventional subspecies
Journal of Zoology, 2009Co-Authors: Roger S. ThorpeAbstract:Ordination analysis of the geographic variation in the Western Grass Snake reveals a V pattern with the northern populations at the apex and the south-eastern (Italian) populations differentiated clinally down one arm and the south western (Ibero-African) populations differentiated categorically along the other arm. There is a clear relationship between latitude and extent of differentiation; the populations in the south west being particularly highly differentiated. These phenetic patterns can be closely related to the numerically hypothesized phylogeny and can be explained by Pleistocene events. The relationship between the rejected conventional subspecies and these patterns is discussed and it is shown that some conventional subspecies are derived from arbitrarily sectioned clines and delimited by inappropriate physiographic features.
