Scanning electron microscopic and cytochemical analyses of alveolar and peritoneal macrophages of mice, dogs and cats.

Alveolar and peritoneal macrophages (MPs) of mouse, dog and cat were compared in relation to their scanning electron microscopic features and the lysosomal activities of nonspecific esterase, acid phosphatase, and β-glucuronidase. The long spindle shape of peritoneal MPs differed from the spherical form of alveolar MPs in all species. There was no difference in the morphological findings among the three animals. Murine alveolar and peritoneal MPs were strongly positive for all three enzymes. Canine and feline alveolar and peritoneal MPs were strongly positive for acid phosphatase and β-glucuronidase, but weakly positive for nonspecific esterase. These results strongly suggest that acid phosphatase and β-glucuronidase can be used as markers of the MPs in healthy dogs and cats.