Pulmonary corpora amylacea in sheep.
Pulmonary corpora amylacea (PCA) were found in 36 per cent of lambs with chronic non-progressive pneumonia. They were spheroidal or ovoid, concentrically lamellar, and commonly found in the alveoli. The components of PCA were complex and variable but staining reactions indicated that most of them contained deoxyribonucleoproteins, glycoproteins and ribonucleoproteins. Electron microscopy showed that they were composed of a fine granular material with an occasional vesicular pattern. There are a number of differences in the morphology and staining reaction of ovine PCA compared with those described in man. Some of these differences may be related to their age. Ovine PCA are closely associated with chronic non-progressive pneumonia and it is postulated that they may result indirectly from bronchiolar stenosis and stagnation of exudate.