正常ラットひ臓におけるヘモジデリン貧食マクロファージの分布と加齢にともなう推移

Abstract

In order to understand the splenic structure and pathognomonic changes, and the intrasplenic cell movement, it is important to clarify the intrasplenic distribution of hemosiderin-laden macrophages. Distribution of hemosiderin-laden macrophages was microscopically examined using iron-stained paraffin sections of the spleens of normal rats ranging in age from neonatal to 28 months. In addition, the liver and femoral bone marrow as well as serum iron content were also examined to determine systemic conditions of iron metabolism. Hemosiderin-laden macrophages were found in all splenic compartments, i.e., the periarteriolar Lymphoid sheath (PALS), lymphoid follicles, marginal zone and red pulp. Special attention was paid to the PALS and marginal zone in this study, although hemosiderin was mainly deposited in the red pulp. Hemosiderin-laden macrophages were rarely found until rats were 3 months old, and increased in number thereafter. According to a morphometric quantitative measurement of hemosiderin using an image analyzer, hemosiderin deposition peaked at 12 months in the red pulp and at 20 months in the PALS and marginal zone. Hemosiderin deposition in the PALS and marginal zone was one-ninth to one-fourth that in the red pulp. Hemosiderin-laden macrophages were present in the lymphoid follicles beginning at 2 months. Around the artery at the splenic hilus, hemosiderin-laden macrophages appeared even at 1 month, when hemosiderin was rarely found in the red pulp and other compartments. Hemosiderin deposition increased in the PALS even at 20 and 28 months when the deposition decreased in other compartments. Early hemosiderin deposition around the artery at the splenic hilus and increase in hemosiderin deposition with age in the PALS represent an accumulation of hemosiderin resulting from lymphatic flow from the PALS to the hilus.