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Ultrastructural study of ovine pulmonary
pasteurellosis: involvement of neutrophils and macrophages
A. Gázquez, E. Redondo, S. Martínez and L. Gómez
Histology and Pathological Anatomy Unit, Faculty of Veterinary
Sciences, Uex. Cáceres, Spain
Offprint requests to: Luis
Gómez, Histología y Anatomía Patológica,
Facultad de Veterinaria, Uex, Avda de la Universidad s/n, 10071,
Cáceres, Spain. e-mail: lui@unex.es
Summary. Pasteurellosis is a common infectious disease
characterised by fibrinous pneumonia and involving neutrophils
and macrophages. This study aimed to determine the timing and
extent of the pathogenic involvement of these cell elements in
lesions induced in experimentally-infected lambs.
A concentration of approximately 3x108 bacteria/ml. was inoculated
into 30 two-month-old disease-free Merino lambs. Five lambs were
assigned to each of five experimental batches, slaughtered on
days 1, 3, 7, 11 and 15 following intratracheal inoculation, and
to one control batch inoculated with a sterile solution. One control
animal was slaughtered at the same time as each experimental batch.
More characteristic lesions occur in bronchioles, peribronchial
tissue and alveoli and are characterised by fibrinous processes.
From the start of the experiment, epithelial-cell disruption and
loss of microvilli were apparent; cell debris, desquamate cells
and bacterial elements were observed in bronchiolar lumina, embedded
in a fibrillar granular material. Alveolar structures displayed
fewer neutrophils and macrophages, containing phagocytic vacuoles.
Laminar bodies were apparent in type II pneumocytes. The interseptal
area contained similar cell types, as well as abundant edema.
In the course of the experiment, macrophage numbers increased
in all the areas involved, with signs of intense phagocytic activity.
The final phase of the experiment was characterised by a mild
interseptal infiltrate and by clear alveolar lumina. Histol.
Histopathol. 16, 855-860 (2001)
Key words: Neutrophils, Macrophages, Pasteurellosis,
Lung
DOI: 10.14670/HH-16.855
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