title: Alterations in the pulmonary histoarchitecture of neonatal mice exposed to hyperoxia.
abstract: OBJECTIVE
  To analyze the effects of exposure to hyperoxia (100% oxygen) on the lung histoarchitecture of neonatal mice.
  
  
  METHODS
  Neonatal Balb/c mice were exposed to hyperoxia (HG) (100% oxygen) (n= 10) in a chamber (15 x 20 x 30 cm) for 24 hours with a flow of 2 L/min. The control group (CG) (n = 10) was exposed to normoxia in the same type of chamber and for the same time. After exposure, the animals were euthanized by decapitation; the lungs were removed and processed for histological examination according to the laboratory routine. Three-mm thick sections were stained with hematoxylin and eosin (H&E). The morphometric analysis was performed with in order to analyze the macrophages present in the alveolar lumen, surface density (Sv) of gas exchange, volume density (Vv) of lung parenchyma, and areas of atelectasis.
  
  
  RESULTS
  A decrease in the number of alveolar macrophages (MØ) was observed in the HG (HG = 0.08 ±0.01 MØ/mm(2), CG = 0.18 ± 0.03 MØ/mm(2), p=0.0475), Sv of gas exchange in HG (HG = 8.08 ± 0.12 mm(2)/mm(3), CG=8.65 ± 0.20mm(2)/mm(3), p = 0.0233), Vv of lung parenchyma in HG (HG = 54.7/33.5/83.5%/mm(2); CG = 75/56.7/107.9%/mm(2), p<0.0001) when compared with the CG. However, there was an increase in areas of atelectasis in HG (HG = 17.5/11.3/38.4 atelectasis/mm(2), CG = 14/6.1/24.4 atelectasis/mm(2), p=0.0166) when compared with the CG.
  
  
  CONCLUSIONS
  The present results indicate that hyperoxia caused alterations in lung histoarchitecture, increasing areas of atelectasis and diffuse alveolar hemorrhage.
authors.affiliation: Laboratório de Biomorfologia e Patologia Experimental, Centro de Ciências da Saúde, Universidade Severino Sombra (USS), Vassouras, RJ, Brasil.
authors.forename: Renata B
authors.initials: RB
authors.lastname: Reis
authors.forename: Akinori C
authors.initials: AC
authors.lastname: Nagato
authors.forename: Clarissa R
authors.initials: CR
authors.lastname: Nardeli
authors.forename: Isadora C P
authors.initials: IC
authors.lastname: Matias
authors.forename: Wanderson G
authors.initials: WG
authors.lastname: Lima
authors.forename: Frank S
authors.initials: FS
authors.lastname: Bezerra
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D006470:Hemorrhage / Q000209:etiology; D019570:Inhalation Exposure / Q000009:adverse effects*; D008168:Lung / Q000166:cytology / Q000378:metabolism / Q000473:pathology*; D016676:Macrophages, Alveolar / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D023421:Models, Animal; D010100:Oxygen / Q000008:administration & dosage / Q000633:toxicity*; D001261:Pulmonary Atelectasis / Q000209:etiology / Q000473:pathology; D011897:Random Allocation; D018709:Statistics, Nonparametric
chemical_list: D010100:Oxygen