Deciduous dentition and dental eruption sequence in Interatheriinae (Notoungulata, Interatheriidae): implications in the systematics of the group

2021 ◽  
pp. 1-25
Author(s):  
Mercedes Fernández ◽  
Juan C. Fernicola ◽  
Esperanza Cerdeño
Keyword(s):  
Permanent Tooth ◽  
Permanent Dentition ◽  
New Combination ◽  
Deciduous Dentition ◽  
Crown Height ◽  
Dental Eruption ◽  
Posterior Direction ◽  
Anterior Direction ◽  
Posterior Anterior ◽  
Anterior Posterior

Abstract Studies focused on deciduous dentition, ontogenetic series, and tooth eruption and replacement patterns in fossil mammals have lately increased due to the recognized taxonomic and phylogenetic weight of these aspects. A study of the deciduous and permanent dentition of Interatherium and Protypotherium (Interatheriinae) is presented, based mainly on unpublished materials. Deciduous cheek teeth are brachydont and placed covering the apex of the respective permanent tooth; in addition, some morphological and metrical differences are observed along the crown height. Five dental ontogenetic stages are distinguished among the juvenile specimens on the basis of the degree of wear, the replacement of the deciduous premolars, and the eruption of the molars. The crown height and the wear degree of different Interatheriinae taxa show: (1) eruption pattern of molars in an anterior–posterior direction (M/m1 to M/m3); (2) pattern of replacement of deciduous premolars and eruption of permanent premolars in a posterior–anterior direction (dP/dp4 to dP/dp2 and P/p4 to P/p2); and (3) eruption of M/m3 before the replacement of dP/dp4. Results allow evaluating the diagnostic dental characteristics used to describe some interatheriines, as well as reinterpreting some taxonomic assumptions: the holotype of Protypotherium diversidens Ameghino, 1891 is recognized as a juvenile of another species of the genus, and the species is not validated, considering it as Protypotherium sp.; the holotype of Eudiastatus lingulatus Ameghino, 1891 falls in the variability of Protypotherium, becoming P. lingulatus new combination, tentatively maintaining the species and implying the synonymy between Eudiastatus and Protypotherium; and the holotype of Eopachyrucos ranchoverdensis Reguero, Ubilla, and Perea, 2003 is reinterpreted as bearing deciduous premolars.

scholarly journals Giant nerve fibre activity in intact, freely moving earthworms

1978 ◽  
Vol 72 (1) ◽  
pp. 217-227 ◽  
Author(s):  
C. D. Drewes ◽  
K. B. Landa ◽  
J. L. McFall
Keyword(s):  
Nerve Fibre ◽  
Tactile Stimulation ◽  
Longitudinal Contraction ◽  
Giant Fibre ◽  
Posterior Direction ◽  
Freely Moving ◽  
Giant Fibres ◽  
Anterior Direction ◽  
Posterior Anterior ◽  
Anterior Posterior

1. An approach is described for recording and characterizing giant nerve fibre activity in intact, freely moving earthworms. 2. Medial giant fibre (MGF) spikes were conducted in an anterior-posterior direction at a mean rate of 32.2 m/s; lateral giant fibre (LGF) spikes were conducted in a posterior-anterior direction at a mean rate of 12.5 m/s. 3. Rates of giant fibre spike conduction and maximal frequencies of firing (up to 500/s) in intact animals were higher than values previously reported in isolated preparations. 4. MGF spikes were followed 1:1 by presumed giant motor axon spikes and facilitating muscle potentials. 5. Single MGF or LGF spikes evoked by applying tactile stimulation were not accompanied by longitudinal contraction, but a series of two or more MGF spikes or three or more LGF spikes were accompanied by such contractions. 6. MGF and LGF spikes occurred infrequently during locomotory movements in the absence of any experimenter-applied stimulation, suggesting that sensory inputs associated with normal locomotion over an irregular substrate are sufficient to excite giant fibres.

scholarly journals Fused primary first mandibular macromolar with a unique relation to its permanent successors: A rare tooth anomaly

2013 ◽  
Vol 07 (02) ◽  
pp. 239-242 ◽  
Author(s):  
Abhishek Dhindsa ◽  
Shalini Garg ◽  
S. G. Damle ◽  
Shireen Opal ◽  
Tavleen Singh
Keyword(s):  
Permanent Tooth ◽  
Permanent Dentition ◽  
Dental Anomalies ◽  
Supernumerary Tooth ◽  
Deciduous Dentition ◽  
Primary Molar ◽  
Anterior Teeth ◽  
Mandibular First Premolar ◽  
Double Teeth ◽  
Fused Tooth

ABSTRACTDental anomalies of number and forms may occur in the primary and permanent dentition. Various terms have been used to describe dental twinning anomalies: Germination, fusion, concrescence, double teeth, conjoined teeth, twinned teeth, geminifusion, and vicinifusion. Fused tooth is a developmental anomaly that is seen more frequently in the primary than the permanent dentition. Double tooth involving deciduous anterior teeth is found mostly in the mandible.Very few cases of nonsyndromic double primary molar have been reported in the literature. The succeeding permanent tooth is often found missing congenitally in the same region. This article reports a very rare unilateral occurrence of an anomalous, primary mandibular first macromolar formed by fusion with a dysmorphic premolar like supernumerary tooth in deciduous dentition period. Instead of agenesis of succedaneous tooth, the double tooth has been succeeded by normally developing mandibular first premolar in the same region.

Dental ontogeny of harp seals, Phoca groenlandica

1987 ◽  
Vol 65 (6) ◽  
pp. 1425-1434 ◽  
Author(s):  
R. E. A. Stewart ◽  
B. E. Stewart
Keyword(s):  
Permanent Tooth ◽  
Permanent Dentition ◽  
Tooth Eruption ◽  
Harp Seal ◽  
Permanent Teeth ◽  
Deciduous Teeth ◽  
Deciduous Dentition ◽  
Phoca Groenlandica ◽  
Number Of Teeth ◽  
Dental Ontogeny

Harp seal fetuses and neonates were examined to determine the development, resorption, and eruption characteristics of deciduous and permanent dentition. Early September fetuses had recently formed, deciduous teeth only. By early December the deciduous dentition was robust and enameled. Permanent teeth were also present. In late December the roots of the deciduous teeth were being resorbed and the permanent dentition was larger and better developed. About 80% of the deciduous teeth were resorbed by birth in March. The rest were resorbed or shed after birth. The pattern of permanent tooth eruption was not correlated with pup age but the total number of teeth erupted increased significantly with increasing pup age, from 38% in newborns to 100% in weaned pups about 3 weeks old. The neonatal line formed at birth rather than at weaning or the onset of moult.

scholarly journals Alveolar bone pathology associated with delayed permanent tooth eruption in a cat – a case study

2021 ◽  
Vol 90 (4) ◽  
pp. 415-420
Author(s):  
Anna S. Spirina ◽  
David A. Crossley
Keyword(s):  
Alveolar Bone ◽  
Permanent Tooth ◽  
Permanent Dentition ◽  
Tooth Eruption ◽  
Bone Pathology ◽  
Dental Eruption ◽  
Delayed Eruption ◽  
Unerupted Teeth

A young cat was presented with oral discomfort, gingival swelling and delayed eruption of the permanent dentition. Radiography confirmed the presence of unerupted teeth and identified alveolar bone pathology. Operculotomy was performed to expose the embedded teeth. Eruption and the potential etiology of disturbances to normal dental eruption are discussed.

Effects of assistive devices on postural control following a balance disturbance along the anterior-posterior direction

2021 ◽  
Vol 90 ◽  
pp. 239-244
Author(s):  
Yunju Lee ◽  
Rachel Badr ◽  
Brianna Bove ◽  
Patrick Jewett ◽  
Meri Goehring
Keyword(s):  
Postural Control ◽  
Assistive Devices ◽  
Posterior Direction ◽  
Anterior Posterior

scholarly journals A standardized nomenclature for cervical spine soft-tissue release and osteotomy for deformity correction

2013 ◽  
Vol 19 (3) ◽  
pp. 269-278 ◽  
Author(s):  
Christopher P. Ames ◽  
Justin S. Smith ◽  
Justin K. Scheer ◽  
Christopher I. Shaffrey ◽  
Virginie Lafage ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Soft Tissue ◽  
Interrater Reliability ◽  
Soft Tissue Release ◽  
Spine Deformity ◽  
Intrarater Reliability ◽  
Perfect Agreement ◽  
Moderate Agreement ◽  
Posterior Anterior ◽  
Anterior Posterior

Object Cervical spine osteotomies are powerful techniques to correct rigid cervical spine deformity. Many variations exist, however, and there is no current standardized system with which to describe and classify cervical osteotomies. This complicates the ability to compare outcomes across procedures and studies. The authors' objective was to establish a universal nomenclature for cervical spine osteotomies to provide a common language among spine surgeons. Methods A proposed nomenclature with 7 anatomical grades of increasing extent of bone/soft tissue resection and destabilization was designed. The highest grade of resection is termed the major osteotomy, and an approach modifier is used to denote the surgical approach(es), including anterior (A), posterior (P), anterior-posterior (AP), posterior-anterior (PA), anterior-posterior-anterior (APA), and posterior-anterior-posterior (PAP). For cases in which multiple grades of osteotomies were performed, the highest grade is termed the major osteotomy, and lower-grade osteotomies are termed minor osteotomies. The nomenclature was evaluated by 11 reviewers through 25 different radiographic clinical cases. The review was performed twice, separated by a minimum 1-week interval. Reliability was assessed using Fleiss kappa coefficients. Results The average intrarater reliability was classified as “almost perfect agreement” for the major osteotomy (0.89 [range 0.60–1.00]) and approach modifier (0.99 [0.95–1.00]); it was classified as “moderate agreement” for the minor osteotomy (0.73 [range 0.41–1.00]). The average interrater reliability for the 2 readings was the following: major osteotomy, 0.87 (“almost perfect agreement”); approach modifier, 0.99 (“almost perfect agreement”); and minor osteotomy, 0.55 (“moderate agreement”). Analysis of only major osteotomy plus approach modifier yielded a classification that was “almost perfect” with an average intrarater reliability of 0.90 (0.63–1.00) and an interrater reliability of 0.88 and 0.86 for the two reviews. Conclusions The proposed cervical spine osteotomy nomenclature provides the surgeon with a simple, standard description of the various cervical osteotomies. The reliability analysis demonstrated that this system is consistent and directly applicable. Future work will evaluate the relationship between this system and health-related quality of life metrics.

Using mastoid vibration can detect the uni/bilateral vestibular deterioration by aging during standing

2021 ◽  
pp. 1-10
Author(s):  
Yufeng Lin ◽  
Mukul Mukherjee ◽  
Nicholas Stergiou ◽  
Jung Hung Chien
Keyword(s):  
Balance Control ◽  
Short Axis ◽  
Confidence Ellipse ◽  
Old Adults ◽  
Dependent Variables ◽  
Posterior Direction ◽  
Control Patterns ◽  
Main Effects ◽  
Ellipse Area ◽  
Anterior Posterior

BACKGROUND: The mastoid vibration (MV) has been used to investigate unilateral vestibular dysfunction by inducing nystagmus. Additionally, this MV can be used to quantify the effect of deterioration by aging on the vestibular system during walking. Could such MV be used to assess the uni/bilateral vestibular deterioration by aging during standing? OBJECTIVE: This study attempted to determine the feasibility of using MV for identifying the uni/bilateral vestibular deterioration by aging during standing. METHODS: Fifteen young and ten old adults’ balance control patterns were assessed by three random MV conditions: 1) No MV; 2) Unilateral MV; 3) Bilateral MV. The dependent variables were the 95% confidence ellipse areas and the sample entropy values, which were calculated based on the center of gravity displacement within each condition. RESULTS: Significant main effects of MV and aging were found on all outcome variables. A significant interaction between aging and different MV types was observed in the 95% confidence ellipse area (p = 0.002) and the length of the short axis (anterior-posterior direction, p = 0.001). CONCLUSIONS: We concluded that the MV could be used to identify different vestibular dysfunctions, specifically in old adults.

scholarly journals Derivation of a finite-element model of lingual deformation during swallowing from the mechanics of mesoscale myofiber tracts obtained by MRI

2010 ◽  
Vol 109 (5) ◽  
pp. 1500-1514 ◽  
Author(s):  
Srboljub M. Mijailovich ◽  
Boban Stojanovic ◽  
Milos Kojic ◽  
Alvin Liang ◽  
Van J. Wedeen ◽  
...  
Keyword(s):  
Finite Element ◽  
Connective Tissue ◽  
Diffusion Tensor ◽  
Element Model ◽  
Out Of Plane ◽  
Posterior Direction ◽  
Elastic Constraints ◽  
The Relationship ◽  
Passive Muscle ◽  
Anterior Posterior

To demonstrate the relationship between lingual myoarchitecture and mechanics during swallowing, we performed a finite-element (FE) simulation of lingual deformation employing mesh aligned with the vector coordinates of myofiber tracts obtained by diffusion tensor imaging with tractography in humans. Material properties of individual elements were depicted in terms of Hill's three-component phenomenological model, assuming that the FE mesh was composed of anisotropic muscle and isotropic connective tissue. Moreover, the mechanical model accounted for elastic constraints by passive and active elements from the superior and inferior directions and the effect of out-of-plane muscles and connective tissue. Passive bolus effects were negligible. Myofiber tract activation was simulated over 500 ms in 1-ms steps following lingual tip association with the hard palate and incorporated specifically the accommodative and propulsive phases of the swallow. Examining the displacement field, active and passive muscle stress, elemental stretch, and strain rate relative to changes of global shape, we demonstrate that lingual reconfiguration during these swallow phases is characterized by (in sequence) the following: 1) lingual tip elevation and shortening in the anterior-posterior direction; 2) inferior displacement related to hyoglossus contraction at its inferior-most position; and 3) dominant clockwise rotation related to regional contraction of the genioglossus and contraction of the hyoglossus following anterior displacement. These simulations demonstrate that lingual deformation during the indicated phases of swallowing requires temporally patterned activation of intrinsic and extrinsic muscles and delineate a method to ascertain the mechanics of normal and pathological swallowing.

Proton Dose Conversion Coefficients Based on Chinese Reference Adult Woman Voxel Phantom

2013 ◽  
Author(s):  
Fangfang Liu ◽  
Mingqi Shen ◽  
Taosheng Li ◽  
Chunyu Liu
Keyword(s):  
Effective Dose ◽  
Reference Data ◽  
Absorbed Dose ◽  
The Body ◽  
Adult Woman ◽  
Voxel Model ◽  
Conversion Coefficients ◽  
Computational Phantoms ◽  
Posterior Anterior ◽  
Anterior Posterior

In order to calculate the dose conversion coefficients for proton, the voxel model of Chinese Reference Adult Woman (CRAW) was established by the Monte Carlo transport code FLUKA according to the Chinese reference data and the Asian reference data. Compared with the reference data, the deviations of the mass for organs or tissues of CRAW is less than ±5%. Calculations have been performed for 14 incident monoenergetic protons energies from 0.02GeV to 10TeV at the irradiation incident of anterior-posterior (AP) and posterior-anterior (PA). The results of fluence-to-effective dose conversion coefficients are compared with data from the different models such as an anthropomorphic mathematical model, ICRP reference adult voxel model, the voxel-based visible Chinese human (VCH). Anatomical differences among various computational phantoms and the spatial geometric positions of the organs or tissues lead to the discrepancies of the effective dose conversion coefficients in the ranging from a negligible level to 107% at proton energies below 0.2GeV. The deviations of the coefficients, above 0.2GeV, are mostly within 10%. The results of fluence-to-organ absorbed dose conversion coefficients are compared with the data of VCH. The deviations of the coefficients, below and above 0.2GeV, are within 150% and 20%, respectively. The primary factors of the deviations for the coefficients should be due to the differences of the organ mass and the size of the body shape.

The polarity of the dental lamina in the regenerating salamander jaw

Development ◽  
1973 ◽  
Vol 30 (3) ◽  
pp. 635-646
Author(s):  
Heber T. Graver
Keyword(s):  
Normal Tissue ◽  
Ambystoma Maculatum ◽  
Dental Lamina ◽  
Reversed Polarity ◽  
The Right ◽  
Anterior Direction ◽  
Anterior Posterior

In ¼ and ½ amputated lower jaws of larval Ambystoma maculatum the dental lamina (DL) is replaced from both the anterior and posterior ends of the regenerate area, while in adult Triturus viridescens the DL is regenerated from the posterior stump tissues only. One-fourth and ½ mandibular jaw amputations were performed in such a manner that a short stump of jaw, devoid of DL, remained. Larvae exhibited a posterior regrowth of the DL, while in adults the lamina accumulated at the edge of the regenerate but did not enter the new tissue. Transplantation of a section of jaw from the left to the right side of the mandible resulted in the DL of the inserted piece having a reversed polarity in its new position. In both larval and adult forms, the DL of the transplant established connexions both anteriorly and posteriorly with lamina present. Transverse amputations through the inserted piece resulted in regeneration from the DL in the transplant in an anterior direction. Transplantation of a section of edentulous tissue into normal jaw tissue of the opposite side, or ttansplantation of a section of normal tissue into the edentulous area of the opposite side resulted in no anterior of posterior regrowth of the DL into the edentulous area. Collectively the results indicate that no anterior–posterior polarity exists in the DL of the larval salamander jaw, since regeneration can occur equally well in both directions. The DL of the adult salamander jaw exhibits an anterior–posterior polarity allowing for regrowth in an anterior direction only.

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