title: Evaluation of histological changes after tracheal occlusion at different gestational ages in a fetal rat model.
abstract: OBJECTIVE
  To evaluate the histological changes of tracheal cartilage and epithelium caused by tracheal occlusion at different gestational ages in a fetal rat model.
  
  
  METHODS
  Rat fetuses were divided into two groups: a) External control, composed of non-operated rats, and b) Interventional group, composed of rats operated upon on gestational day 18.5 (term = 22 days), divided into triads: 1) Tracheal occlusion, 2) Internal control and 3) Sham (manipulated but not operated). Morphological data for body weight, total lung weight and total lung weight/body weight ratio were collected and measured on gestational days 19.5, 20.5 and 21.5. Tracheal samples were histologically processed, and epithelial, chondral and total tracheal thicknesses were measured on each gestational day.
  
  
  RESULTS
  The tracheal occlusion group exhibited an increase in total lung weight/body weight ratio (p<0.001). Histologically, this group had a thicker epithelial thickness (p<0.05) and thinner chondral (p<0.05) and total tracheal thicknesses (p<0.001). These differences were more prominent on gestational days 20.5 and 21.5.
  
  
  CONCLUSIONS
  Tracheal occlusion changed tracheal morphology, increased epithelial thickness and considerably decreased total tracheal thickness. These changes in the tracheal wall could explain the development of tracheomegaly, recently reported in some human fetuses subjected to tracheal occlusion.
authors: University of São Paulo, School of Medicine of Ribeirão Preto, Division of Pediatric Surgery, Department of Surgery and Anatomy, Ribeirão Preto/SP, Brazil.
authors: Rodrigo Melo
authors: RM
authors: Gallindo
authors: Frances Lilian Lanhellas
authors: FL
authors: Gonçalves
authors: Carolina Teixeira de Resende
authors: CT
authors: Barreto
authors: Augusto Frederico Santos
authors: AF
authors: Schmidt
authors: Luis Antonio Violin Dias
authors: LA
authors: Pereira
authors: Lourenço
authors: L
authors: Sbragia
mesh_terms: D000367:Age Factors; D000818:Animals; D001835:Body Weight; D005333:Fetus / Q000033:anatomy & histology / Q000196:embryology / Q000601:surgery*; D005865:Gestational Age; D008168:Lung / Q000033:anatomy & histology / Q000196:embryology; D023421:Models, Animal; D009929:Organ Size; D051381:Rats; D015203:Reproducibility of Results; D060205:Therapeutic Occlusion / Q000009:adverse effects / Q000379:methods*; D013997:Time Factors; D014132:Trachea / Q000033:anatomy & histology / Q000196:embryology / Q000601:surgery*