Characterization of Sonic hedgehog expressing cell lineages progeny detected in the forming mouse mandibular bone

This thesis characterizes cell populations participating during the ossification of the mouse jaw at the tooth-bone interface in relation to their developmental origin. The aim of the thesis was to evaluate whether the cell populations participating in the formation of the tooth-bone interface area of the nascent jaw during development belong to cell lines that expressed Sonic Hedgehog (Shh) in the past and to determine whether these Shh descendant cells actively participate in the ossification processes in the nascent jaw bone area ─ whether they are osteoblasts, osteocytes or osteoclasts. Using Cre- loxP system, we were able to detect Shh descendant cells in the area of the mouse mandible and maxilla. Using a combination of RNA scope and immunohistochemistry, we demonstrated that a part of the population of Shh descendant cells at the tooth- bone interface of the first molar in both jaws belongs to cells participating in the formation and maintenance of the bone matrix ─ that they are osteoblasts and osteocytes. Part of the population of Shh descendent cells also belonged to the population of osteoclasts involved in bone resorption in the area of the developing tooth germs. The results of this work bring new insights into the understanding of the role of Shh in the tooth-bone interface and may be...