scholarly journals VIII—The development and morphology of the teeth of Ornithorhynchus *

1937 ◽  
Vol 228 (555) ◽  
pp. 367-420 ◽  
Keyword(s):  
Tooth Development ◽  
Enamel Organ ◽  
Individual Animal ◽  
Dental Lamina ◽  
Early Differentiation ◽  
Early Stages ◽  
The Individual

Though tooth development in the mammals has been extensively studied, I had several objects in view when I decided to investigate the details of tooth development in Ornithorhynchus. The following are among the more important considerations which determined me to undertake this work. 1— Early Stages in the Differentiation the Dental Lamina and the Formation of the Enamel Organ The structure of the dental lamina and the stages in the early differentiation of the enamel organ have been carefully examined in representative groups by many observers, and by the beginning of this century the histological appearances of the dental lamina and its adnexa were well known. Yet the significance of some of the structures which are seen in the early stages of tooth development is still uncertain, and widely divergent views have been expressed, not only as to the interpretation of such structures in the individual animal, but also as to their possible value in the light of phylogenetic recapitulation.

Homelessness or Symbolic Castration? Subjectivity, Language Acquisition, and Sociality in Julia Kristeva and Jacques Lacan

Hypatia ◽  
2005 ◽  
Vol 20 (2) ◽  
pp. 69-87 ◽  
Author(s):  
Bettina Schmitz ◽  
Julia Jansen
Keyword(s):  
Language Acquisition ◽  
Jacques Lacan ◽  
Julia Kristeva ◽  
Early Stages ◽  
Patriarchal Society ◽  
Starting Point ◽  
The Individual ◽  
Forms Of Violence

How much violence can a society expect its members to accept? A comparison between the language theories of Julia Kristeva and Jacques Lacan is the starting point for answering this question. A look at the early stages of language acquisition exposes the sacrificial logic of patriarchal society. Are those forces that restrict the individual to be conceived in a martial imagery of castration or is it possible that an existing society critically questions those points of socialization that leave their members in a state of homelessness? The following considerations should help to distinguish between unavoidable and avoidable forms of violence.

Tooth development in the ‘crooked’ mouse

Development ◽  
1977 ◽  
Vol 41 (1) ◽  
pp. 279-287
Author(s):  
J. A. Sofaer
Keyword(s):  
Competitive Inhibition ◽  
Tooth Development ◽  
Tooth Germ ◽  
Axial Skeleton ◽  
Tissue Formation ◽  
Supernumerary Teeth ◽  
Hard Tissue ◽  
Dental Lamina ◽  
Dental Abnormalities ◽  
Rates Of Growth

The semidominant gene ‘crooked’ (Cd) in the mouse produces anomalies of the axial skeleton (resulting in a crooked tail), microphthalmia and dental abnormalities, including small molars with simplified cusp patterns that are equivalent to patterns passed through during normal morphodifferentiation. A series of embryonic litters from Cd/ + × Cd / + matings was used to investigate the embryological basis for the dental abnormalities. Microphthalmic embryos were classed as Cd/Cd, and their most normal litter mates were selected as controls (+ / + or Cd / +). An additional set of control embryos came from the inbred strain CBA/Cam (+ / +). Serial sagittal sections of the heads of these embryos were examined microscopically, and the maximum anteroposterior diameters of the developing upper and lower first molars were measured. Reduction in the rates of growth and morphodifferentiation of Cd/Cd first molars, relative to those of litter mate controls, was associated with the appearance of an adjacent abnormal proliferation of the dental lamina. Some proliferations in older embryos showed signs of early tooth germ formation, but many were seen to have regressed and no examples of supernumerary teeth have been found in Cd/Cd adults. Small size of Cd/Cd molars may therefore result from competitive inhibition of molar growth by a transient abnormal laminal proliferation, and Cd/Cd cusp patterns from the relatively premature onset of hard tissue formation during normal but retarded sequences of morphodifferentiation.

scholarly journals Dentin matrix protein 1 (DMP1) expression in developing human teeth

2009 ◽  
Vol 20 (5) ◽  
pp. 365-369 ◽  
Author(s):  
Elizabeth Ferreira Martinez ◽  
Luciana Alves Herdy da Silva ◽  
Cristiane Furuse ◽  
Ney Soares de Araújo ◽  
Vera Cavalcanti de Araújo
Keyword(s):  
Dental Pulp ◽  
Matrix Protein ◽  
Enamel Organ ◽  
Dentin Matrix Protein 1 ◽  
Tooth Formation ◽  
Dentinal Tubules ◽  
Dental Lamina ◽  
Dentin Matrix Protein ◽  
Dental Papilla ◽  
Dentin Matrix

Dentin matrix protein 1 (DMP1) is an acidic phosphoprotein that plays an important role in mineralized tissue formation by initiation of nucleation and modulation of mineral phase morphology. The purpose of the present study was to examine the immunoexpression of DMP1 in tooth germs of 7 human fetuses at different gestational ages (14, 16, 19, 20, 21, 23 and 24 weeks) comparing with completed tooth formation erupted teeth. The results showed the presence of DMP1 in the dental lamina, as well as in the cells of the external epithelium, stellate reticulum and stratum intermedium of the enamel organ. However, in the internal dental epithelium, cervical loop region and dental papilla some cells have not labeled for DMP1. In the crown stage, DMP1 was expressed in the ameloblast and odontoblast layer, as well as in the dentinal tubules of coronal dentin near the odontoblast area. Erupted teeth with complete tooth formation exhibited immunolabeling for DMP1 only in the dentinal tubules mainly close to the dental pulp. No staining was observed in the enamel, predentin or dental pulp matrix. DMP1 is present in all developing dental structures (dental lamina, enamel organ, dental papilla) presenting few immunoexpression variations, with no staining in mineralized enamel and dentin.

Between Guess Work and Certainty in Psychiatry

PEDIATRICS ◽  
1958 ◽  
Vol 21 (6) ◽  
pp. 949-949
Keyword(s):  
Subject Matter ◽  
Scientific Method ◽  
Individual Animal ◽  
Fundamental Distinction ◽  
The Subject ◽  
The Common ◽  
The Individual ◽  
Rational Inquiry

"The safeguards contained in the scientific method are repugnant to some who devote themselves to psychotherapy, and their argument against it always harks back to the uniqueness of the individual." The author points out that this is an obscurantist argument and it does not follow that because an individual is a unique reality, he cannot be compared with anyone else. On this basis there would be no science of zoology as every individual animal is also a unique reality, but this has not been an obstacle to comparison and collective study in this science. The argument is reminiscent of claims prevalent during the controversies about evolution when the opponents asserted that man was an improper subject for comparitive study because of his fundamental distinction from all other creatures. Only insofar as the common denominators between individuals can be ascertained may the subject matter of psychiatry become the object of scientific and rational inquiry and without this it could not be taught. We would be in the position of having to accept the pronouncements of supposedly singularly gifted individuals on faith, and continuity in the field would presumably depend entirely upon apprenticeship.

The Capacity to Be Alone

2016 ◽  
pp. 241-248 ◽  
Author(s):  
Donald W. Winnicott
Keyword(s):  
The Self ◽  
Human Being ◽  
Early Stages ◽  
Mother Figure ◽  
Protective Environment ◽  
The Individual ◽  
Frequent Reference

Winnicott discusses what makes it possible for the human being to develop a capacity to be alone. He states that, at first, for the infant, there is no experience of its own body as separate from the environment (the mother). But gradually the individual takes in the ego-supportive mother and becomes able to be alone without frequent reference to the mother or mother symbol. To arrive at what Winnicott calls the stage of ‘I am’ in the self, is only possible because of a protective environment from the very early stages onwards, when the mother is preoccupied with the infant and orientated to his ego requirements through her identification with him and his needs. In time the individual becomes able to forgo the actual presence of a mother or mother-figure.

scholarly journals Longitudinal Study of Shiga Toxin-Producing Escherichia coli Shedding in Sheep Feces: Persistence of Specific Clones in Sheep Flocks

2009 ◽  
Vol 75 (6) ◽  
pp. 1769-1773 ◽  
Author(s):  
Sergio Sánchez ◽  
Remigio Martínez ◽  
Alfredo García ◽  
Jorge Blanco ◽  
Jesús E. Blanco ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Longitudinal Study ◽  
Shiga Toxin ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Individual Animal ◽  
Pulsed Field ◽  
The Individual ◽  
Sheep Feces

ABSTRACT To provide information on the persistence and maintenance of colonization with Shiga toxin-producing Escherichia coli (STEC) in sheep, pulsed-field gel electrophoresis analysis of STEC isolates (n = 145) belonging to serogroups O5, O91, and O146 from 39 healthy animals was performed in a 12-month longitudinal study carried out with four sheep flocks. At the flock level as well as the individual-animal level, the same clones were obtained on sampling occasions separated by as much as 11 months.

scholarly journals The Dental Lamina: An Essential Structure for Perpetual Tooth Regeneration in Sharks

2020 ◽  
Vol 60 (3) ◽  
pp. 644-655
Author(s):  
Gareth J Fraser ◽  
Ariane Standing ◽  
Charlie Underwood ◽  
Alexandre P Thiery
Keyword(s):  
Murine Model ◽  
Tooth Development ◽  
Tooth Regeneration ◽  
Regenerative Processes ◽  
Dental Lamina ◽  
Developmental Models ◽  
Nonclassical Models ◽  
Developmental Shift ◽  
Evolutionary Context

Synopsis In recent years, nonclassical models have emerged as mainstays for studies of evolutionary, developmental, and regenerative biology. Genomic advances have promoted the use of alternative taxa for the study of developmental biology, and the shark is one such emerging model vertebrate. Our research utilizes the embryonic shark (Scyliorhinus canicula) to characterize key developmental and regenerative processes that have been overlooked or not possible to study with more classic developmental models. Tooth development is a major event in the construction of the vertebrate body plan, linked in part with the emergence of jaws. Early development of the teeth and morphogenesis is well known from the murine model, but the process of tooth redevelopment and regeneration is less well known. Here we explore the role of the dental lamina in the development of a highly regenerative dentition in sharks. The shark represents a polyphyodont vertebrate with continuously repeated whole tooth regeneration. This is presented as a major developmental shift from the more derived renewal process that the murine model offers, where incisors exhibit continuous renewal and growth of the same tooth. Not only does the shark offer a study system for whole unit dental regeneration, it also represents an important model for understanding the evolutionary context of vertebrate tooth regeneration.

scholarly journals Giant Pindborg Tumor (Calcifying Epithelial Odontogenic Tumor): An Unusual Case Report with Radiologic-Pathologic Correlation

2013 ◽  
Vol 3 ◽  
pp. 11 ◽  
Author(s):  
Satya Ranjan Misra ◽  
Sthitaprajna Lenka ◽  
Sujit Ranjan Sahoo ◽  
Sobhan Mishra
Keyword(s):  
English Literature ◽  
Odontogenic Tumor ◽  
Odontogenic Tumors ◽  
Enamel Organ ◽  
Impacted Tooth ◽  
Calcifying Epithelial Odontogenic Tumor ◽  
Dental Lamina ◽  
Pindborg Tumor ◽  
Maxilla And Mandible ◽  
Epithelial Odontogenic Tumor

Odontogenic tumors develop in the jaws from odontogenic tissues such as enamel organ, Hertwig epithelial root sheath, dental lamina, and so on. A variety of tumors unique to the maxilla and mandible are therefore seen. Calcifying epithelial odontogenic tumor (CEOT) is a rare, aggressive, benign odontogenic tumor of epithelial origin accounting for only about 1% of all odontogenic tumors. It is eponymously called “Pindborg tumor”, as it was first described by Pindborg in 1955. The origin of this locally invasive tumor remains unknown. It is thought to arise from stratum intermedium. It commonly affects the posterior mandible manifesting as a slow-growing asymptomatic swelling often associated with an impacted tooth. We report a case of CEOT, for which, owing to its huge size we have proposed the term “giant” Pindborg tumor (CEOT). This is probably the largest case of this tumor reported so far in the English literature. The present case also has the classic yet rare “driven snow” appearance of the tumor on radiographs.

The apparent digestibility of maize grain when given in various physical forms to adult sheep and cattle

1973 ◽  
Vol 80 (2) ◽  
pp. 259-267 ◽  
Author(s):  
G. F. Wilson ◽  
N. N. Adeeb ◽  
R. C. Campling
Keyword(s):  
Particle Size ◽  
Apparent Digestibility ◽  
Individual Animal ◽  
High Moisture ◽  
Lactating Cows ◽  
Effect Of Particle Size ◽  
Maize Grain ◽  
The Individual ◽  
Maize Kernels ◽  
Male Sheep

SummaryA series of digestibility trials was conducted with non-lactating cows and adult castrated male sheep given diets of hay and dried or high-moisture maize grain in various physical forms. Sheep were able to digest all forms of maize well and to a greater extent than cows. In cows considerable variation in digestibility of maize was associated with the particle size of the maize and the individual animal. Maximum digestibility of dried maize in cows ensued when the modulus of fineness lay within the range 4·7–3·0 and with high moisture maize from 5·4 to 5·1. A study was made of the effect of particle size on the rate of digestion of maize suspended in nylon bags in the rumen. Evidence was presented showing the importance of rumination in ensuring the digestion of intact kernels. Possible causes of differences between cows in their ability to digest intact maize kernels are discussed.

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