Scanning Electron Microscopic and Cytochemical Analyses of Alveolar and Peritoneal Macrophages of Mice, Dogs and Cats.

Abstract

ABSTRACT. 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. -KEY WORDS: canine, cytochemistry, macrophage.J. Vet. Med. Sci. 60(10): 1145-1148, 1998 no abnormal findings in mice. Alveolar and peritoneal MPs were prepared using the methods of McCarron et al. [12] and Tanigawa et al. [19], respectively. In brief, alveolar fluids were obtained by repeated pulmonary lavage with cold phosphate-buffered saline (PBS, pH 7.2, 50-100 ml/ kg). Peritoneal fluids were obtained by washing the peritoneal cavity with cold PBS (50-100 ml/kg) at 3 days after intraperitoneal injection of 1.5% thioglycolate solution (50 mg/kg) in saline. Both fluids obtained were centrifuged, and sediments were washed. Their cellular concentration was countered with a hemocytometer. Light-Giemsa staining showed more than 90% of peritoneal exudate cells to be MPs. The cells were incubated with Dulbecco's modified Eagle's medium (Gibco, Grand Island, NY, U.S.A.), supplemented with 7.5% fetal calf serum (Microbiological Associates, Walkersville, MD, U.S.A.) in tissue culture dishes containing glass cover slips in an atmosphere of 10% CO 2 at 37°C for 2 hr. Scanning electron microscopy: Prepared cells were fixed with 3% glutaraldehyde in a 0.1 M phosphate (pH 7.3) solution for 2 hr and postfixed with 1% osmium tetroxide in the same buffer for 1 hr. After conductive-staining with 2% tannic acid and 1% osmium tetroxide, the cells were dehydrated in a graded series of ethanol baths, then immersed in t-butyl alcohol, and freeze-dried using the tbutyl alcohol freezing drying method [7]. An ion sputter coater was used to coat the dried samples with platinum, and the cells were observed under a field emission scanning electron microscope (HFS-2ST, Hitachi, Tokyo, Japan).Lysosomal enzymes: Prepared cells were fixed with cold 4% paraformaldehyde (pH 7.4) for 5 min and maintained in Holt's gum sucrose. The cells were then stained by the α-naphtyl acetate method [9] for the detection of nonspecific esterase, by the naphthol AS-BI phosphate method [2] for detection of acid phosphatase, and by the naphthol AS-BI β -glucuronidase method [6] for detection of β-glucuronidase. Examination under light microscopy showed

Changes in Murine Hyalocytes Are Valuable Early Indicators of Ocular Disease

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