scholarly journals Incremental growth of therizinosaurian dental tissues: implications for dietary transitions in Theropoda

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4129 ◽  
Author(s):  
Khai Button ◽  
Hailu You ◽  
James I. Kirkland ◽  
Lindsay Zanno
Keyword(s):  
Morphological Evidence ◽  
Thin Sections ◽  
Dental Tissues ◽  
Theropod Dinosaurs ◽  
Crown Volume ◽  
Dietary Strategy ◽  
Incremental Growth ◽  
Dental Microstructure ◽  
Dinosaur Teeth ◽  
Tooth Growth

Previous investigations document functional and phylogenetic signals in the histology of dinosaur teeth. In particular, incremental lines in dentin have been used to determine tooth growth and replacement rates in several dinosaurian clades. However, to date, few studies have investigated the dental microstructure of theropods in the omnivory/herbivory spectrum. Here we examine dental histology of Therizinosauria, a clade of large-bodied theropods bearing significant morphological evidence for herbivory, by examining the teeth of the early-diverging therizinosaurian Falcarius utahensis, and an isolated tooth referred to Suzhousaurus megatherioides, a highly specialized large-bodied representative. Despite attaining some of the largest body masses among maniraptoran theropod dinosaurs, therizinosaurian teeth are diminutive, measuring no more than 0.90 cm in crown height (CH) and 0.38 cm in crown base length (CBL). Comparisons with other theropods and non-theropodan herbivorous dinosaurs reveals that when controlling for estimated body mass, crown volume in therizinosaurians plots most closely with dinosaurs of similar dietary strategy as opposed to phylogenetic heritage. Analysis of incremental growth lines in dentin, observed in thin sections of therizinosaurian teeth, demonstrates that tooth growth rates fall within the range of other archosaurs, conforming to hypothesized physiological limitations on the production of dental tissues. Despite dietary differences between therizinosaurians and hypercarnivorous theropods, the types of enamel crystallites present and their spatial distribution—i.e., the schmelzmuster of both taxa—is limited to parallel enamel crystallites, the simplest form of enamel and the plesiomorphic condition for Theropoda. This finding supports previous hypotheses that dental microstructure is strongly influenced by phylogeny, yet equally supports suggestions of reduced reliance on oral processing in omnivorous/herbivorous theropods rather than the microstructural specializations to diet exhibited by non-theropodan herbivorous dinosaurs. Finally, although our sample is limited, we document a significant reduction in the rate of enamel apposition contrasted with increased relative enamel thickness between early and later diverging therizinosaurians that coincides with anatomical evidence for increased specializations to herbivory in the clade.

The relationships of Uronemus : A Carboniferous dipnoan with highly modified tooth plates

1987 ◽  
Vol 317 (1185) ◽  
pp. 299-327 ◽  
Keyword(s):  
Tissue Type ◽  
Close Relative ◽  
Marginal Tooth ◽  
Thin Sections ◽  
Scanning Electron Microscope Study ◽  
Air Breathing ◽  
Dental Tissues ◽  
Lower Jaw ◽  
Tooth Plate ◽  
Evolutionary Phase

Previous accounts of the dentition of the Carboniferous dipnoan Uronemus have stressed the significance of the scattered small denticles. These, together with the marginal teeth and ridges, have been interpreted as primitive characters of the dipnoan dentition shared with three other genera: the Devonian Uranolophus and Griphognathus and the Carboniferous to Permian Conchopoma . Genera with tooth plates have been considered to be a monophyletic group in which tooth plates are a derived character; Uronemus has been excluded from this group in all previous investigations dealing with the significance of the dentition for determining relationships among dipnoans. The macromorphology of the dentition of Uronemus has been re-examined and correlated with the histology of all the dental tissues. Optical study of thin sections and scanning electron microscope study of the adjacent cut surfaces has shown that the hard, wear-resistant dentine of the teeth and ridges is petrodentine. The arrangement, growth, wear and histology of the dental tissues have been compared with those of denticulated and tooth-plated genera. The arrangement of new teeth relative to the tooth ridge, the pattern of wear along the ridge, and the type of dentine and its growth indicate that the dentition of Uronemus is best interpreted as a tooth plate with one long lingual tooth ridge and reduced lateral tooth rows. Therefore the marginal tooth ridges are not considered to be homologous with those of denticulate dipnoans such as Uranolophus . The presence of petrodentine, a tissue type only found in forms with tooth plates, is consistent with the view that the dentition is derived by modification of a radiate tooth plate. The denticles covering restricted regions of the palate and lower jaw are considered to have been a secondary acquisition. The suggestion that Conchopoma is a close relative of Uronemus is not accepted, and possible new relationships have been proposed. New data on Scaumenacia and Phaneropleuron , two other genera previously compared with Uronemus , are presented. Rhinodipterus , a form with elongate lingual ridges, is also discussed. Phaneropleuron is shown to have radiate tooth plates and not a marginal row of conical teeth as previously described. It is proposed that the tooth plate of Uronemus is derived from a dipterid type of plate. A discussion of some of the other factors involved in determining the relationships of the genus is given. From an examination of the use of the tongue for respiration and feeding by the extant Lepidosiren paradoxa , it is concluded that many features of dipnoan evolution in the tooth-plated lineage result from the adoption of air breathing after an early evolutionary phase of gill respiration, and that Uronemus was adapted for air breathing. The ‘denticulated’ lineage, which included genera such as Uranolophus and Griphognathus , shows none of the skeletal features associated with the presence of a tongue, and presumably did not become air breathing.

scholarly journals Electron microscopic study of human lung tissue after in vitro exposure to elastase.

1993 ◽  
Vol 41 (6) ◽  
pp. 851-866 ◽  
Author(s):  
S M Morris ◽  
P J Stone ◽  
G L Snider
Keyword(s):  
Animal Models ◽  
Lung Tissue ◽  
Human Lung ◽  
Basement Membranes ◽  
Morphological Evidence ◽  
Elastic Fibers ◽  
Human Neutrophil Elastase ◽  
Human Lung Tissue ◽  
Thin Sections

Much of the experimental evidence supporting the hypothesis that pulmonary emphysema results from an imbalance between elastases and anti-elastases in the lung comes from animal models. The present study was designed to examine the effects on human lung tissue of the two elastases that have been most widely used to produce these animal models. Lung tissue was exposed in vitro to human neutrophil elastase (HNE) or porcine pancreatic elastase (PPE). Although both enzymes solubilized protein at similar rates, PPE solubilized elastin five times faster than did HNE. Ultrastructurally, HNE-exposed tissue exhibited fewer damaged elastic fibers as well as some fibers that were damaged at the edges, whereas the interior of the fiber appeared intact. Elastic fibers showing damage only at the periphery were not seen in tissue exposed to PPE. Immunocytochemical studies in which antibodies to HNE and PPE were applied to thin sections of Lowicryl-embedded tissue indicated that both of these elastases could be detected in association with elastic fibers, but only in areas of the fiber that showed morphological evidence of elastase injury. Both HNE and PPE removed fibronectin from basement membranes (as determined by loss of binding of fibronectin antibodies after exposure to elastase), but neither elastase was detected on basement membrane. Loss of epithelial cells usually accompanied elastic fiber damage by HNE but not PPE.

The role of carbohydrate-protein biopolymers and hyaluronic acid at the resistance formation of hard dental tissues against pathological processes of carious and non-carious genesis

10.12737/7378 ◽  
2014 ◽  
Vol 8 (1) ◽  
pp. 0-0
Author(s):  
Лещева ◽  
E. Leshcheva ◽  
Ипполитов ◽  
I. Ippolitov ◽  
Ипполитов ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Soft Tissues ◽  
Human Tooth ◽  
Cationic Protein ◽  
Thin Sections ◽  
Tooth Structure ◽  
Dental Tissues ◽  
Protein Nature ◽  
Hard Dental Tissues ◽  
Special Studies

At the series of histochemical studies hypothesis of existence of a "cationic protein" in human tooth structure and set of its amino acids components and hyaluronic acid has been checked. Taking into account histogenesis and cytogeny of tooth structure and the earlier results received from the epidermis and multilayer partly keratinous epithelium of the oral mucosa, special studies had been created, based on the original equipment preparation of paraffin sections, and thin sections of the whole teeth and modified histochemical identification technology of carbohydrate-protein biopolymers in hard dental tissues. Histological slides are prepared from extracted for orthodontic indications teeth. Sectioned and examined thin sections of teeth has investigated in transmitted light for issues related to topochemistry of carbohydrate-protein biopolymers and hyaluronic acid concerning the distribution in structures of enamel, dentin, predentin, cellular and acellular cement. Identified carbohydrate-protein biopolymers and substances of protein nature objectively fill inter prismatic enamel areas, dentin tubules and their walls, localized in the cement structure of tooth and its soft tissues forming a physiologi-cal barrier to microorganisms and their metabolic products as in the demineralizing processes as for the mechan-ical interventions during the vital activity and medical interventions.

scholarly journals Reconstructing skeletal fiber arrangement and growth mode in the coral <i>Porites lutea</i> (Cnidaria, Scleractinia): a confocal Raman microscopy study

2012 ◽  
Vol 9 (11) ◽  
pp. 4885-4895 ◽  
Author(s):  
M. Wall ◽  
G. Nehrke
Keyword(s):  
Polarized Light ◽  
Organic Matrix ◽  
Sample Surface ◽  
Raman Microscopy ◽  
Growth Patterns ◽  
Confocal Raman Microscopy ◽  
Porites Lutea ◽  
Thin Sections ◽  
Incremental Growth ◽  
Confocal Raman

Abstract. Confocal Raman microscopy (CRM) mapping was used to investigate the microstructural arrangement and organic matrix distribution within the skeleton of the coral Porites lutea. Relative changes in the crystallographic orientation of crystals within the fibrous fan-system could be mapped, without the need to prepare thin sections, as required if this information is obtained by polarized light microscopy. Simultaneously, incremental growth lines can be visualized without the necessity of etching and hence alteration of sample surface. Using these methods two types of growth lines could be identified: one corresponds to the well-known incremental growth layers, whereas the second type of growth lines resemble denticle finger-like structures (most likely traces of former spines or skeletal surfaces). We hypothesize that these lines represent the outer skeletal surface before another growth cycle of elongation, infilling and thickening of skeletal areas continues. We show that CRM mapping with high spatial resolution can significantly improve our understanding of the micro-structural arrangement and growth patterns in coral skeletons.

Green Pigmentation in Human Teeth. A Stereomicroscopic Study

2014 ◽  
Vol 38 (4) ◽  
pp. 355-361 ◽  
Author(s):  
A Rakauskaite ◽  
G Juodzbalys ◽  
DH Pauza ◽  
M Cicciù
Keyword(s):  
Current Knowledge ◽  
Current Status ◽  
Primary Tooth ◽  
Human Teeth ◽  
Thin Sections ◽  
Dental Tissues ◽  
Microscopic Features ◽  
Proper Diagnosis ◽  
Uncommon Condition ◽  
Hard Dental Tissues

Green pigmentation in teeth is an uncommon condition associated with bilirubin deposits in hard dental tissues. Its occurrence can cause anxiety to both the child and parents and is not diagnosed easily by clinicians. The aim of this study is to analyze the current knowledge about the etiology, the intraoral alterations, and the macroscopic and microscopic features of green teeth pigmentation related to a high bilirubin levels. A primary tooth was extracted and manually sliced into 600 microns thin sections. The slenderized slices were examined with a light microscope AxioImager M1 to evaluate the microscopic teeth structure. The clinical characteristics of teeth may help in the diagnosis of current or past systemic diseases. Pediatricians should be able to quickly note the signs in order to perform the proper diagnosis. This study may help clinicians gain more knowledge about the current status of this uncommon pathology.

scholarly journals EFFECTS OF CALCIUM-CONTAINING FIXATION SOLUTIONS ON CHOLINERGIC SYNAPTIC VESICLES

1974 ◽  
Vol 63 (3) ◽  
pp. 780-795 ◽  
Author(s):  
Alan F. Boyne ◽  
Timothy P. Bohan ◽  
Terence H. Williams
Keyword(s):  
Binding Sites ◽  
Synaptic Vesicles ◽  
Chelating Agents ◽  
Electric Organ ◽  
Morphological Evidence ◽  
Nerve Terminals ◽  
Vesicle Membrane ◽  
Dense Particle ◽  
Thin Sections ◽  
Electron Dense Particle

Calcium (Ca)-containing fixation solutions applied to slices of electric organ of the electric ray, Narcine brasiliensis, have been shown to have three distinct ultrastructural effects on cholinergic synaptic vesicles of the nerve terminals. (a) An electron-dense particle (EDS) is observed within the vesicle; the particle is seen in unosmicated, unstained tissues and can be removed from thin sections by Ca-chelating agents. It is concluded that the EDS represents Ca bound by the vesicle. It is suggested that the bound ATP of the vesicle provides anionic Ca binding sites. (b) The vesicle membrane tends to ‘crinkle’ or collapse depending on the concentration of the other components of the fixative solution. The ‘crinkling’ or collapse are largely reversed by a wash step in the absence of Ca. (c) The presence of Ca results in the appearance of a population of vesicles which form characteristic fusions or ‘tight’ junctions with the terminal membrane. This appears to be morphological evidence for the proposal, which has been frequently put forward, that Ca facilitates such a fusion before discharge of vesicle-bound transmitter. With the discovery that the use of Ca-containing fixatives leads to the demonstration of a subpopulation of synaptic vesicles fused to the terminal membrane, we are led to propose that this is the ultrastructural location of the newly synthesized acetylcholine which has been shown by others to be preferentially released by stimulation.

scholarly journals The preparation for parallel thin sections of undecalcified dental tissues

1970 ◽  
Vol 20 (2) ◽  
pp. 191-200
Author(s):  
Toshibumi ISHII ◽  
Shigeru YOSHIDA ◽  
Hideo OSHIO ◽  
Tatuo SHIRAISHI
Keyword(s):  
Thin Sections ◽  
Dental Tissues

scholarly journals Catecholamine innervation of enkephalinergic neurons in guinea pig hypothalamus: demonstration by an in vitro autoradiographic technique combined with a post-embedding immunogold method.

1988 ◽  
Vol 36 (5) ◽  
pp. 533-542 ◽  
Author(s):  
V Mitchell ◽  
J C Beauvillain ◽  
P Poulain ◽  
M Mazzuca
Keyword(s):  
Guinea Pig ◽  
Ultrastructural Level ◽  
Microscopic Level ◽  
Electron Microscopic Level ◽  
Morphological Evidence ◽  
Osmic Acid ◽  
Electron Microscopic ◽  
Double Labeling ◽  
Thin Sections

To study the relationship between the catecholamine (CA) nerve endings and the enkephalinergic cell bodies in the magnocellular dorsal nucleus (MDN) of guinea pig hypothalamus, double-labeling experiments were performed on the same tissue section at the electron microscopic level. An in vitro autoradiographic (ARG) method for [3H]-norepinephrine (NE) or [3H]-dopamine (DA) was combined with a post-embedding immunogold cytochemical technique for Met-enkephalin (Met-enk) in colchicine-treated animals. Hypothalamic slices (450 micrograms) were perfused with [3H]-NE or [3H]-DA at the fluid-gas interface, then fixed by immersion with glutaraldehyde and osmic acid. Semi-thin sections processed from the thickness of the slices showed adequate penetration of the tracers to all parts of the tissue. Frontal sections permitted visualization of some CA-uptake structures distributed around the cells. At the ultrastructural level, preservation appeared good on about 60% of the thickness of slices, and [3H]-CA structures were easily distinguished. Ultra-thin sections were successively incubated with Met-enk and colloidal gold-labeled antisera, followed by ARG processing. At the electron microscopic level, the good integrity of the tissue made possible visualization of [3H]-CA nerve terminals making synaptic contacts with enkephalinergic perikarya. These results provide morphological evidence for direct catecholaminergic control of enkephalinergic neurons of the MDN.

Ultrastructure of the Parotid Gland of the Nine-Banded Armadillo

1977 ◽  
Vol 35 ◽  
pp. 640-641
Author(s):  
J. R. Ruby
Keyword(s):  
Endoplasmic Reticulum ◽  
Parotid Gland ◽  
Periodic Acid ◽  
Acinar Cells ◽  
Duct System ◽  
Parotid Glands ◽  
Dasypus Novemcinctus ◽  
Anterior Portion ◽  
Periodic Acid Schiff ◽  
Thin Sections

Parotid glands were obtained from five adult (four male and one female) armadillos (Dasypus novemcinctus) which were perfusion-fixed. The glands were located in a position similar to that of most mammals. They extended interiorly to the anterior portion of the submandibular gland.In the light microscope, it was noted that the acini were relatively small and stained strongly positive with the periodic acid-Schiff (PAS) and alcian blue techniques, confirming the earlier results of Shackleford (1). Based on these qualities and other structural criteria, these cells have been classified as seromucous (2). The duct system was well developed. There were numerous intercalated ducts and intralobular striated ducts. The striated duct cells contained large amounts of PAS-positive substance.Thin sections revealed that the acinar cells were pyramidal in shape and contained a basally placed, slightly flattened nucleus (Fig. 1). The rough endoplasmic reticulum was also at the base of the cell.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

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