title: An open-ended rat tracheal implant model: toxic effects of formaldehyde on the respiratory epithelium.
abstract: An open-ended rat tracheal implant model was developed to permit quantitative and repetitive exposure of respiratory epithelia to test substances of a variety of physical forms. To investigate the acute toxicity of formaldehyde with this new model, tracheas were exposed to formaldehyde solutions twice a week, for up to 12 weeks. At the higher formaldehyde concentrations (1.0, 0.6, 0.3%) the tracheal lumens became obstructed by granulation tissue. At the lower concentrations (0.2, 0.1, 0.01%), the appearance of flattened and atrophic epithelium as well as hyperplasia and squamous metaplasia were observed. The extent of these epithelial alterations was, for the most part, formaldehyde dose-dependent.
mesh_terms: D000818:Animals; D004848:Epithelium / Q000187:drug effects / Q000473:pathology; D005260:Female; D005557:Formaldehyde / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D011916:Rats, Inbred F344; D012137:Respiratory System / Q000187:drug effects*; D014132:Trachea / Q000187:drug effects* / Q000473:pathology / Q000637:transplantation; D014140:Tracheotomy
chemical_list: D005557:Formaldehyde