Th.--Sci. nat.--Lille 1, 1977. N°: 369.

M.Sc. (Botany) / Please refer to full text to view abstract

Call number: LD2668 .T4 1978 W33 / Master of Science

No description available.

Eighty normal cheek teeth and 26 normal incisors extracted from 14 donkeys (median age 19 years) at post mortem were anatomically examined including grossly and by computerised axial tomography (CAT) imaging. Decalcified histology was performed on 54 sections from 18 teeth (8 donkeys), undeclacified histology on 16 sections from 7 donkeys and scanning electron microscopy on 10 sections from 10 teeth (3 donkeys). The dental formulae and tooth number was found to be the same as in horses with a higher prevalence (17 %) of canine teeth in female donkeys. A decrease in tooth length, pulp horn length and pulp horn width with age was illustrated, as was an increase in occlusal secondary dentine depth with age, although not all these age changes were statistically significant. Normal histological and ultrastructural features of donkey teeth were identified and found to be similar to equine findings. Enamel was found to be thicker buccally in both maxillary and mandibular cheek teeth. Quantitative measurements of transverse dentine thickness around pulp cavities, dentinal tubule diameters and densities, and enamel prism diameters were made. Left lower incisors (301) were extracted from 7 donkeys and 6 horses for micro-hardness determination of enamel, primary and secondary dentine using a Knoop Hardness indenter. No significant difference between donkey and horse incisor microhardness was demonstrated. Examination of 19 donkey skulls at post mortem examination showed donkeys to have a higher degree of anisognathia (27%) compared to horses (23%). Post mortem dental examination of 349 donkeys (median age 31) demonstrated a high prevalence of dental disease (93%) and in particular cheek teeth diastemata (85%). Furthermore, age was associated with increasing prevalence of dental disease and diastemata. Diastemata were also associated with the presence of other dental disorders and with colic-related death in affected donkeys. Quantitative measurements of 45 diastemata from 16 donkeys showed no difference in the medial and lateral width of diastemata but periodontal pockets were deeper laterally. The definition of valve and open diastemata were confirmed. Pulp exposure, dental caries and periodontal disease were examined in detail (54 skulls) at post mortem. A total of 19 teeth were extracted for further detailed examination as performed in normal anatomy. Clinical dental examinations were performed on 357 donkeys in the U.K. that were selected for age distribution, and the prevalence of dental disease in different age groups was found to increase from 28% in the youngest group (age 0-10 years) to 98% in the oldest group (age > 35 years). An increased prevalence of most dental disorders with age was demonstrated as was an association between dental disease and weight loss, poor body condition score, supplemental feeding and previous episodes of colic. Clinical dental examination of 203 working donkeys in Mexico showed similar types of dental disorders as found in the U.K. study, with dental disease present in 62%, of which 18% required urgent dental treatment. There was a significant association between age groups and dental disease, and age groups and body condition score, but there was no association between dental disease and body condition score. However, body condition score was not associated with supplemental feeding or faecal egg counts either.

No description available.

A detailed row by row investigation of major lateral tooth cusp mineralisation, together with the concomitant development of the superior epithelial tissue surrounding the teeth of the chiton Acanthopleura hirtosa has been undertaken using a combination of light microscopy, and scanning and transmission electron microscopy. A holistic approach has been adopted that encompasses observations over a range of spatial scales, from whole radula mineralisation processes to those occurring within individual tooth cusps at various stages of development. In addition, mineralisation in radulae from freshly collected animals has been compared to that of animals maintained for extensive periods within a newly developed iron limited system, which restricts radula mineralisation without impeding the formation of the organic matrix. An evaluation of the iron limitation technique has revealed that maintaining specimens of A. hirtosa within an iron poor environment results in a significant departure from the normal pattern of mineralisation in these animals. As a consequence of iron limitation, there is an obvious increase in the number of unmineralised tooth rows in addition to associated alterations in structure and composition at all stages of tooth development. In normal specimens of A. hirtosa, the onset of mineralisation in the tooth cusps occurs following the prior accumulation of iron at the junction zone and the sudden accumulation of iron containing granules in the cusp epithelium at tooth row 13. The superior epithelium surrounding the tooth cusps undergoes a series of developmental changes leading up to, and following, the onset of mineralisation. In particular, the abundance of mitochondria within the apical cusp epithelium increases, presumably in order to provide the ideal conditions of pH, and thus solubility, needed for the supersaturation of iron and its nucleation at row 13. Once mineralisation has commenced, the microvilli attached to the cusps develop rapidly, and are suggested to do so in order to facilitate the transport of iron, and thereby ensure that a high concentration gradient of this element into the cusps is maintained. The delivery of iron into the cusps occurs from two fronts, the first from the superior epithelium via the posterior surface, and the second from the junction zone via an internal pathway situated along the lepidocrocite boundary between the magnetite and core regions of the tooth. The existence of a plume of elements between this internal mineralisation pathway and the junction zone, provides the first direct evidence that the junction zone is involved in the storage and release of elements for cusp mineralisation. Data from iron limited radulae also indicate that iron continues to be deposited at the junction zone in preference to the superior epithelium or cusps, despite the disruption of mineralisation, highlighting the importance of this region in the mineralisation process. Iron reinstatement experiments have also shown that the internal pathways of iron delivery within the organic matrix remain viable, despite prolonged periods of iron limitation. In addition, the reinstatement of iron has revealed that the plumes, situated between the junction zone and internal mineralising pathway of the cusp, stem from the centre of the plate like junction zone, directly above the stylus canal, a tube like cavity situated within the styli of each major lateral tooth. An in depth study of the stylus canal has revealed that cells within the canal are remarkably similar to those of the epithelium surrounding the cusps, suggesting that this structure may also be involved in the delivery of ions to the junction zone. The stylus canal is shown to be present in the major lateral tooth cusps of 38 chiton species distributed worldwide, and is therefore likely to be a feature common to all chitons. The presence of the canal, and indeed its absence from the bases of all remaining non iron mineralised teeth, irrespective of chiton species, also points strongly to a functional relationship between the stylus canal and tooth cusp mineralisation.

Substratum effects of micro- and nano-scaled structures on mammalian cell lines have experienced rapid developments during past decades. Tremendous studies have shown that micro- and nano- scaled surface morphology has great influences on cellular behavior and has great potential application in medical device design and organs regeneration. Although a variety of cell types have been used in cell-substrate studies for different purposes, information about how the cellular response of hepatic cells to the nanoporous and microgrooved structures is still insufficient The effects of groove/ridge width of the microgrooved structures on the mammalian cell culturing is usually overlooked. In this thesis, the cellular response of hepatic cells to the nanoporous and microgrooved is studied, including the cell spreading, cell elongation, cell alignment, and cell motility. Also, the effects of groove/ridge width are addressed on three mammalian cell lines (BEL-7402, MIHA, and HeLa). Three experiments were performed. Firstly, the effect of nanoporous surface on hepatic cell line, BEL-7402, was studied. The nanoporous surface (140 nm) was fabricated by anodize alumina membrane and microcontact printing techniques on PDMS surface. Cellular behaviors were analyzed with scanning electron microscope and time-lapse imaging. The results showed that cell projected area was reduced with cell migration speed was promoted on porous surface when compared with flat control surface. Secondly, the effect of microgrooves surface (10 μm, 30 μm and 50μm, with equal ridge and groove width) on hepatic cell line, BEL-7402, was studied. The microgrooved surface was fabricated by microcontact printing on PDMS. Cellular behaviors were analyzed with scanning electron microscope and time-lapse imaging. The results showed that cell elongation, alignment and directional migration was promoted by the groove structure when comparing with flat surface. Thirdly, the effect of microgrooved PDMS surfaces with varied ridge width and groove width on three mammalian cell lines (BEL-7402, MIHA, and HeLa)was studied. Microgrooved PDMS surfaces with nine combination of ridge width (5 μm, 10 μm and 30 μm) and groove width (5 μm, 10 μm and 30 μm) were fabricated using photolithography and soft lithography. The results showed that all grooved structures have almost same affection on the cellular response, independent of the cell type. Also, our result showed that the cell elongation displayed same pattern on all micrgrooved surfaces, independent of the groove/ridge width changes. In addition, our result showed that microgrooved surface that contained 10 μm ridge or groove were less effective in aligning cells. On the other hand, microgrooved surface 5×5, 5×30, 30×5 and 30×30 showed most effective in aligning cell when compare with other grooved surface and flat control surface. Our result provide information on how cell response to surface morphology at nano-scale and micro-scale. These informations are highly conducive for the liver regeneration, cancer metastasis study, and other tissue engineering research. / published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / Anatomy / Master / Master of Philosophy

The extracellular matrix (ECM) is the material found surrounding the cells in a tissue. One component of the ECM is the elastic fiber, which confers the property of elasticity to its environment. Organs such as the lung, skin and major blood vessels have an abundance of elastic fibers so that they are able to expand and recoil. Elastic fibers are composed of two main components; elastin and microfibrils. Microfibrils are composed primarily of fibrillin-1 and provide a scaffold unto which tropoelastin monomers assemble. Elastic fibers interact with many other proteins in the ECM, one of which is fibulin-5. Based on the severe elastic fiber defects observed in the fibulin-5 null mouse, it was established that fibulin-5 plays an essential role in elastic fiber development. This role may be in the deposition of tropoelastin onto microfibrils and/or in stabilizing the elastic fibers in the extracellular matrix. In the present study, the relationship between fibulin-5 and the elastic fiber was investigated through a number of in vivo and in vitro experiments. To test the hypothesis that fibulin-5 requires the presence of elastin to assemble in the ECM, full-length recombinant fibulin-5 (rF5) was purified from transfected cells and used to make a fibulin-5 antibody. Solid-phase binding assays using rF5 showed that fibulin-5 binds tropoelastin at two sites; the initial portion of the C-terminus and the first calcium-binding epidermal growth factor-like domain at the N-terminus. Immunofluorescence staining of elastin null mouse embryonic fibroblast cultures revealed that fibulin-5 does not require elastin to be present in the ECM in order to assemble. Subsequently, solid-phase binding assays showed that fibulin-5 can bind to the N-terminus of fibrillin-1. To determine if fibulin-5 could exist independent of elastin and/or fibrillin-1 in vivo, an immunohistochemical analysis was conducted on heart, liver, lung, colon, spleen, testis and kidney. All three proteins were co-localized in all organs except in the kidney, where fibrillin-1 was found to independently stain the capillary tufts of the renal corpuscles and renal tubules. Thus, fibulin-5 may be co-regulated with elastin and is not present on elastin-independent microfibrils. Additionally, novel locations of elastic fibers were uncovered in the heart, liver, colon, spleen and testis. Overall, this study provides important insights as to the role of fibulin-5 in elastic fiber structure and assembly and also reveals the complexity in understanding the pathogenesis of diseases involving elastic fiber proteins.