ULTRASTRUCTURAL-CHANGES IN THE LUNG IN NIEMANN-PICK TYPE-C MOUSE

The biochemical and morphological aspects of BALB/c mice with many fea tures of the Niemann-Pick disease type C in man (NP-C mouse) have been studied extensively. However, the pulmonary pathology has not been st udied extensively and we describe here some unique ultrastructural fea tures; of the lung in the NP-C mouse. Ultrastructurally, macrophages i n younger mice contained osmiophilic dense granules and annulolamellar structures, but larger multilamellar concentric structures increased in the macrophages of older mice. In contrast, endothelial cells and t ype I pneumocytes showed membrane-bound bodies with dense granules and vesicular or vesiculogranular structures as well as amorphous materia ls. Type II pneumocytes were unremarkable throughout. Our study sugges ts that endothelial cells and type I pneumocytes are the major site of meta belie derangement resulting in pronounced morphological changes with granular and round membranous structures in the lungs of NP-C mou se. Alveolar macrophages with multilamellar concentric structures may be a result of disturbed disposal of surfactant material from type II pneumocytes rather than that from storage material of type I pneumocyt e.