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The hepatic wedge biopsy of a 3 1/2-year-old boy with fucosidosis was studied by electron microscopy. The cytoplasm of liver parenchymal cells is filled with various forms of membrane-invested storage elements measuring up to 3 μm in diameter. In these storage elements large central deposits of reticulogranular material are surrounded by a narrow peripheral ring of electron-dense material. Others contain numerous lamellar structures with parallel and/or concentric orientation, opaque globules and vesicular structures. Typical peribiliary dense bodies (lysosomes) are generally absent. The storage elements appear to be produced by deposition of storage material in lysosomes. The absence of the lysosomal enzyme α-L-fucosidase is in favor of this concept. Kupffer cells, epithelial cells of the bile canalicular system, vascular endothelial cells of portal tracts and histiocytes are rich in storage elements which are also found in the majority of fibrocytes and fibroblasts. They are uncommon in pericytes and cannot be demonstrated in smooth muscle and fat-storing cells. Ultrastructural features and cellular distribution of storage elements are compared with previous descriptions of related storage disorders.

The presence of gold was investigated in sections of the adrenal glands from rats which had been exposed to intraperitoneal sodium aurothiomalate (32 to 120 mg). Gold was histochemically detected in cortical endocrine cells, chromaffin cells and in fibroblasts and macrophages of both the cortex and medulla. Invisible traces of gold were silver enhanced by autometallography making them readily visible at both the light and electron microscopic levels. The intracellular staining intensity was dose-dependent. In general, the number as well as the staining intensity of individual cells, were highest in the zona glomerulosa and zona reticularis. In gold-containing cells the silver-amplified deposits were present in lysosomes.

We studied the proliferative response of fibroblasts and mesothelial cells in the mesentery of streptozotocin-diabetic rats with diabetes of 4 weeks duration, after local mast-cell secretion elicited by compound 48/80. Free peritoneal mast cells from the diabetic animals showed no altered content of 5-HT, histamine, or heparin, and the concentration of histamine in the mesentery and its release by 48/80 were roughly similar in non-diabetic and diabetic animals. The diabetic animals showed an increased responsiveness in this strictly mast-cell dependent mitogenesis, as measured by specific DNA activity and the mitotic index, regardless of whether the animals were insulin-deficient or treated for 2 h with fast-acting insulin.

Independent of age epithelial cells of normal human seminal vesicles can contain extremely enlarged polyploid and polymorph nuclei, which are able to simulate cells of an anaplastic carcinoma when appearing in aspiration biopsies of the prostate. These nuclear changes are caused by mitotic disturbances, which apparently originate in alterations of cell proliferation.

Freeze-fracture and thin sections were performed on human bone marrow of chronic megakaryocytic-granulocytic myelosis (CMGM) to study the three-dimensional fine structure and maturation of normal and atypical megakaryocytes and thrombocytes. In the many normally maturing megakaryocytes the development of the demarcation membrane system (DMS) was best investigated by comparison of thin sections with freeze-fracture replicas. The DMS shows no connections with the Golgi apparatus or rough-surfaced endoplasmic reticulum, but originates from tubular infoldings of the plasma membrane. These infoldings are always in continuity with the extracellular space and form an intracellular membranous pool by branching and coalescing of flattened tubules from which finally the perforated cisternae of the DMS arise. Freeze-fracture of the normal thrombocytes confirms earlier findings. The abnormal giant platelets seen in CMGM display extensive areas of smooth membranes of a spongy structure consisting of dense tubules surrounded by the labyrinth of the surface-connected system. Their physiological significance in these atypical platelets remains unsolved.

A case of multiple myeloma with a mediastinal tumor and other unusual findings is described. The findings included the presence of extramedullary tumor masses at multiple sites in addition to the medullary tumor and, more interestingly, the occurence of pleural and peritoneal effusions. The plasma cells from these effusions were analyzed using stereological morphometric methods. The plasma cells were also cultured and established as a continuous cell line and were studied using the same methods. Our results indicate that there are qualitative and quantitative morphologic differences between the pleural and peritoneal plasma cells. Comparison between plasma cells and cultured cells from the intraperitoneal exudate showed marked morphologic differences. The analysis of these differences indicated that mature plasma cells, when subjected to culture, were transformed into immature lymphoid cells.

Vesicular cartilage in rickets contains two types of chondrocytes differing morphologically from the surrounding normal hypertrophic cartilage cells. The juxtametaphyseal chondrocytes in rickets are compressed. Their matrix shows deposits of minerals, whereas the mineralisation of metaphyseal osteoid in the neighborhood is only scanty. In addition, fibrillary elements with an atypical periodicity of 750–780 Å are found in the matrix of rachitic epiphyseal plate. A primary alteration of cell metabolism in chondrocytes leading to a defect synthesis of ground substance and resulting in an inhibition of résorption and calcification of cartilage is suggested. Im rachitischen Blasenknorpel lassen sich zwei besondere Chondrocytenformen abgrenzen, die morphologisch von den regelrechten Chondrocyten dieses Epiphysenfugenbereiches abweichen. Die metaphysennahen Blasenknorpelzellen einer rachitischen Epiphysenfuge werden zusammengestaucht. In der Matrix ihrer Lacunenwände finden sich Mineralablagerungen, wohingegen das metaphysenwärts angrenzende Osteoid kaum zu mineralisieren scheint. Ferner können in der Grundsubstanz rachitischer Epiphysenfugen fibrilläre Elemente beobachtet werden, die in einer Periodik von 750–780 Å gebändert sind. Es wird vermutet, daß in einer rachitischen Epiphysenfuge der Zellstoffwechsel einzelner Chondrocyten verändert wird. Infolgedessen tritt eine Störung der Grundsubstanzsynthese ein, was eine Hemmung der Knorpelresorption und Knorpelverkalkung nach sich zieht.

Ultrastructural abnormalities of human respiratory tract cilia have been studied in 33 patients: 21 were adults, 18 with chronic bronchitis, and 12 were children, two with situs inversus. Abnormalities, such as the lack of a few dynein arms or the loss of a peripheral doublet were observed quite frequently in both children and adults. However, congenital abnormalities associated with the “immotile cilia syndrome” were rare and were observed in only three of the children and none of the adults.

A histochemical study of enzymatic activities was undertaken in five cases of histiocytosis X (two localized bone forms, two generalized forms, and one involving mainly the skin), each of which revealed characteristic structural features at the optical and ultrastructural levels. A confirmation was made of the original assumption of high acid α-D-mannosidase activity, i.e. activity described in human Langerhans intraepidermal cells (Elleder, 1975). In the control group of tumors, with the exception of urticaria pigmentosa, enzyme activity was either at trace level or altogether absent. Acid α-D-mannosidase activity therefore appears to be the first biochemical feature common to both histiocytosis X and the Langerhans cells. The significance of the finding for the present theory of the histogenesis of the above tumors is discussed.