Lung oedema – microscopic detection

Abstract

During routine inhalation toxicity studies, microscopic examination of tissues from lungs which have shown small, but statistically significant increases, in organ weight has failed to show evidence of any pathological change. Historically, increases, thought to be due to mild oedema, have been difficult to identify microscopically. A method suitable for dealing with large numbers of rodents has been developed, which can detect microscopically changes associated with small increases in lung weight. The lungs were inflated with formalin vapour and fixed in 10% buffered formalin. Histological processing methods were varied to obtain the best demonstration of oedema. Fixation methods were compared using alpha-naphthylthiourea-induced oedematous lungs. The left lobe was inflated with formalin vapour and the rest of the lung was distended with 10% buffered formalin. The best demonstration of oedema followed formalin vapour fixation. Evidence of oedema, indicated by lung weight increases of approximately 10%, was seen microscopically in formalin-vapour-fixed lungs, but was not seen in the lobes distended with 10% buffered formalin. Application of this technique to other species including cats and dogs has also proved successful.

Combustion-derived flame generated ultrafine soot generates reactive oxygen species and activates Nrf2 antioxidants differently in neonatal and adult rat lungs

“…Lungs were inflated with 37% formaldehyde vapor bubbled under 30 cm hydrostatic pressure for 1 hour as previously described [70,71]. Samples were stored in 1% paraformaldehyde for less than 24 hours prior to tissue processing and paraffin embedment.…”

Eighty-five day postexposure follow-up study in Fischer 344 rats after repeated exposures to methyl isocyanate vapor.

“…The only principal difference was the less frequent squamous metaplasia and submucosal fibroplasia in the bronchioles of male rats exposed for 4 days compared to those exposed for 8 days. There was also a greater frequency of regenerative epithelial hyperplasia in the lungs and tracheas of the female rats exposed for 8 days than was observed in the 4-day exposed animals (Fig.…”

“…Perivascular edema, congestion, and pneumonia in the FIGURE 8. Suppurative bronchopneumonia extending from the bronlung of a male rat that died 10 days following 8 The fact that edema and hyaline membrane deposits were observed in some of the rats that died following repeated exposures to MIC vapor is a noteworthy difference from those animals that were sacrificed, and probably contributed to the death of the rats by respiratory insufficiency. The infusion of lungs with 10% NBF, as was performed in these studies, is not considered the most appropriate method for detection of lung edema because infusion tends to remove evidence of mild pulmonary edema (8).…”

Novel multi-functional europium-doped gadolinium oxide nanoparticle aerosols facilitate the study of deposition in the developing rat lung

“…The trachea was cannulated, thorax opened and lung removed en bloc for inflation with 37% formaldehyde vapor bubbled under 30 cm hydrostatic pressure for 1 hour as previously described. 16, 50, 51 Samples were stored in 1% paraformaldehyde for no more than 24 hours prior to tissue processing and paraffin embedment. Paraffin blocks were sectioned at 4 μm onto poly-L-lysine coated slides, H&E stained and imaged with an Olympus BH2 microscope.…”