Kupffer cells are the sinusoidal macrophages of the liver. Using ultrastructural phosphatase cytochemical methods, we examined the relationships between the Golgi apparatus, GERL, and lysosomes of Kupffer cells in fetal rat livers identified, in part, by their ability to phagocytize intravenously injected latex spheres. Thiamine pyrophosphatase (TPPase) activity was localized to the inner Golgi saccules and some vesicles in the Golgi region but not to GERL. A TPPase-like activity, demonstrable in lysosomes, was abolished by sodium fluoride but not suppressed by the alkaline phosphatase inhibitors L-cysteine and L-p-bromotetramisole. Acid phosphatase (AcPase) was localized to GERL, some coated vesicles, and in lysosomes, but not to the Golgi stacks. Continuities between GERL and lysosomes were observed. Phagosomes containing internalized latex spheres received TPPase and AcPase sequentially. TPPase was localized in phagosomes immediately after latex administration. AcPase activity was not found here until at least 10 minutes following the injection of the particulates. Our findings indicate that Kupffer cell lysosomes are derived from GERL, but also suggest that phagosomes may receive material packaged by the Golgi apparatus as well as GERL.
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