title: The effect of retinoic acid on mouse mandibular molar development in vitro, using alkaline phosphatase as a molecular indicator of differentiation.
abstract: BACKGROUND
  An excellent model system that links evolutionary biology and developmental biology in seeking to understand evolutionary diversity is the study of tooth development in mammals. These studies reflect the diversity of mammalian radiations which bear on the interpretation of South African fossil hominids. Tooth development occurs via epithelio-mesenchymal interactions and involves the production of many substances, including alkaline phosphatase, which is necessary for dentine and enamel formation. Retinoic acid is a known morphogen and is important in tooth development. In excess, retinoic acid has been found to alter the formation of teeth.
  
  
  OBJECTIVE
  In order to determine whether retinoic acid has any effect on tooth morphology, exogenous retinoic acid was administered to developing mouse molar teeth in vitro, and alkaline phosphatase was utilized as an indicator of differentiation.
  
  
  METHODS
  Molars were microdissected from 15.5 day mouse embryo mandibles and cultured at the air: medium interface with or without retinoic acid for seven days. Following fixation and embedding, the explants were sectioned for morphological analysis. Alkaline phosphatase activity was detected using a modified Gomori's histochemical method.
  
  
  CONCLUSIONS
  Retinoic acid appeared to retard the growth and differentiation of the molar explants. This was coincident with reduced alkaline phosphatase.
authors.affiliation: School of Anatomical Sciences, University of the Witwatersrand, Johannesburg. dmjones99@gmail.com
authors.forename: D M
authors.initials: DM
authors.lastname: Jones
authors.forename: B
authors.initials: B
authors.lastname: Fabian
authors.forename: B
authors.initials: B
authors.lastname: Kramer
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis / Q000187:drug effects*; D000565:Ameloblasts / Q000187:drug effects / Q000473:pathology; D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000187:drug effects; D003771:Dental Papilla / Q000187:drug effects / Q000473:pathology; D003804:Dentin / Q000187:drug effects / Q000196:embryology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D005260:Female; D007641:Keratolytic Agents / Q000494:pharmacology*; D008334:Mandible; D051379:Mice; D023421:Models, Animal; D008963:Molar / Q000187:drug effects / Q000473:pathology; D009804:Odontoblasts / Q000187:drug effects / Q000473:pathology; D009805:Odontogenesis / Q000187:drug effects*; D009924:Organ Culture Techniques; D011247:Pregnancy; D012997:Solvents / Q000494:pharmacology; D014083:Tooth Germ / Q000187:drug effects / Q000473:pathology; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D007641:Keratolytic Agents; D012997:Solvents; D014212:Tretinoin; D000469:Alkaline Phosphatase; D004121:Dimethyl Sulfoxide