Better choice of fixatives provides better histological details of the alveolar-capillary interface.
OBJECTIVE
To evaluate lung disease, pulmonary tissues should be fixed by inflation. However, many histological sections prepared after inflation fixation show wire-like alveolar septa with capillary collapse. We investigated the reason for this artefact.


METHODS
To evaluate the effect of fixatives, we used the following commercially available solutions: regular 10% neutral buffered formalin (NBF), 20% NBF, 10% and 5% formalin prepared by diluting the 20% NBF, modified formalin solution as a substitute for 10% NBF, and 10% formalin prepared by diluting the 100% formalin without any buffers.


RESULTS
The osmolarity of the fixative was found to be responsible for the collapse artefact. Ten per cent formalin, prepared by diluting 100% formalin, the commercially available substitute for 10% NBF, and 5% formalin prepared by diluting 20% NBF, yielded the best pulmonary tissue morphology, including that of the alveolar-capillary interface.


CONCLUSIONS
Pulmonary physicians and pulmonary pathologists should use a suitable fixative solution for obtaining a better pulmonary architecture as well as to preserve the tissue block in optimal condition for future assessment of pulmonary diseases.
Hayashi
Tomayoshi
T
Department of Pathology, Nagasaki University Hospital, Nagasaki, Sakamoto, Japan. toma@net.nagasaki-u.ac.jp
Nagayasu
Takeshi
T
Kohno
Shigeru
S
Abe
Kuniko
K
Tamaru
Naoe
N
Anami
Masanobu
M
Sakai
Yasuhiro
Y
Ohbayashi
Chiho
C
D016477:Artifacts; D002196:Capillaries / Q000473:pathology*; D005404:Fixatives / Q000737:chemistry; D005557:Formaldehyde / Q000737:chemistry; D006801:Humans; D009994:Osmolar Concentration; D011650:Pulmonary Alveoli / Q000098:blood supply*; D016707:Tissue Fixation / Q000379:methods*
D005404:Fixatives; D005557:Formaldehyde