In vivo organogenesis is based on the temporal-spatial developmental processes that depend on cell behaviour, for example on their growth, migration, differentiation and intercellular interactions. Such behaviour is regulated by appropriate transient expression of various signalling molecules. Despite the significant advances in therapeutic strategies, the secret of the development of the biological replacement of a damaged or missing tooth has not yet been revealed. In this context, animal models provide a powerful tool for studying tooth normogenesis and pathogenesis in both basic and applied research. Early development of the tooth shares similar morphological and molecular features with other ectodermal organs. At the same time, these features are largely preserved also between species, which is advantageous for the use of model organisms. The dental formula of both: the human and the mouse are reduced against a common ancestor, but both groups of organisms evince simple as well as multicusped teeth. In both, structures called rudimentary were found. These structures are suppressed during ontogenetic development and generally they are not attributed to essential functions. That is why we aimed to study dental rudiments in detail and reveal their function in odontogenesis. This work presents new...

Tidigare forskning har visat att hög contextual interference försämrar den omedelbara prestationen vid ackvisitionen av en färdighet, men främjar inlärning jämfört med låg contextual interference. Resultaten från tillämpad forskning är dock mångtydig och det råder oklarhet i när och i vilka sammanhang effekten uppstår. Syftet med denna positivistiska studie var att jämföra två övningsstrategier med olika grad av contextual interference vid inlärning av rudiments för trumspel. Vuxna musikhögskolestudenter (N=17) med begränsad erfarenhet av trumspel delades in i två grupper – seriell (n=8) och blockindelad (n=9). Uppgiften var att lära sig spela tre rudiment. Den blockindelade gruppen övade sex minuter på varje rudiment en gång, medan den seriella gruppen övade en minut på varje rudiment sex gånger. Deltagarnas retention testades direkt efter och 48 timmar efter övningen. Båda grupperna spelade signifikant snabbare mellan förtest och retentionstesten (p<.01) men det fanns ingen signifikant interaktion mellan grupp och mättillfälle (p=.96) vilket betyder att båda grupper blev lika mycket bättre. I diskussionen redovisas ett antal möjliga förklaringar till varför effekten inte visade sig i denna studie. / Previous research has found that high contextual interference hinders performance at acquisition but promotes learning compared to low contextual interference. The findings in applied research is however ambiguous and there’s uncertainty of when and in which contexts the effect occurs. The purpose of this study was to compare two practice strategies with different levels of contextual interference. Adult college music students (N=17) with limited experience playing drums were divided in to two treatment groups – serial (n=8) and blocked (n=9). The task was to learn to play three drum rudiments. The blocked group practiced each rudiment for six minutes one time while the serial group practice each rudiment for one minute six times. Retention tests were performed immediately after and 48 hours after acquisition. Both groups played significantly faster at retention compared to pre-test (p<.01) but there was no significant interaction between group and test (Pre-test to retention) (p=.96) meaning both groups improved equally. In the discussion a number possible of explanations as to why the effect wasn’t observed are presented.

My PhD thesis has addressed specific questions regarding cell proliferation and tissue dynamics in three key areas of craniofacial development: during suppression and revitalization of tooth buds that develop in the mouse embryonic dentition as rudiments of lost premolars; during dental papilla and follicle formation of the first mouse molar; and during origin of palatal rugae on the mouse hard palate. By evaluation of cell proliferation, we recorded a change in the proliferation pattern along the cheek region of the mandible between less and more advanced embryos at embryonic day 13.5. Thus during the time period, when the development of the large mouse rudimental premolar primordium (R2) is stopped, we showed that the arrest of the rudiment R2 is caused by exhibiting low rate of cell proliferation and high rate of apoptosis. When Sprouty gene signalling is disrupted, the premolar primordium shows rates of proliferation and apoptosis similar to the growing first molar. The R2 subsequently revitalizes and develops into a supernumerary tooth in front of the first molar. Furthermore, we discovered that the dental mesenchyme is very dynamic tissue during bud and cap stages of tooth development and that the dental papilla of the first molar originates only from a restricted region of the dental...