Cytochemical analysis of organelle degradation in phagosomes and apoptotic cells of the mucoid epithelium of mice.

The activity of mitochondrial cytochrome oxidase and peroxisomal catalase in the phagolysosomes and apoptotic bodies of mucoid epithelial cells was analysed. Tissue from 2-6 day old mice was used. The activity of acid phosphatase in lysosomes was also estimated. Cytochrome oxidase was demonstrated in well-preserved mitochondria inside phagosomes. Mitochondria in cells exhibiting apoptotic death also show activity of cytochrome oxidase. The enzyme activity in swollen mitochondria ceases before the membranes of the cristae disappear completely. Apoptotic bodies are phagocytosed by sister mucoid cells and, later on, they are digested inside the cell. Phagosomes which contain already degraded mitochondria show still active catalase in sequestered peroxisomes. The acid phosphatase involved in degradation of phagocytosed material originates from endocytosed lysosomes and primary and secondary lysosomes which fuse with the membranes of phagosomes.