The lacunar cells and its relationship to interdigitating reticulum cells

Lacunar cells, which are characteristic of the nodular sclerosis type of Hodgkin's disease, were investigated by light and electron microscopy and by enzyme cytochemical and immunohistochemical methods. Characteristic ultrastructural features of the lacunar cells were its size, its multilobated nucleus, and the pale cytoplasm containing only a few organelles. These features distinguish the lacunar cell from typical Sternberg-Reed and Hodgkin cells. Enzyme cytochemically, lacunar cells were weakly positive for acid phosphatase and non-specific esterase. the reaction product was distributed either diffusely or more focally in the cytoplasm. By immunostaining, kappa, lambda, and IgG could be detected in some lacunar cells. The immunostaining pattern was bitypic, which might have resulted from non-specific uptake. All the results of the present study indicate that lacunar cells are non-lymphoid cells. When lacunar cells were compared with cells of normal lymphoid tissue, their ultrastructure was found to be very similar to that of interdigitating reticulum cells. Both cell types showed a bizzarrely shaped nucleus and an electron-transparent cytoplasm with only some vesicles and tubules. Furthermore, lacunar cells and interdigitating reticulum cells exhibited a similar reaction pattern of acid phosphatase and non-specific esterase. Thus, from a cytologic and enzyme cytochemical point of view, a direct relationship between the two cell types is very likely.     

Ultrastructure and function of interdigitating cells in the guinea pig thymus.

Electron micrsocopic investigation of the thymus of normal guinea pigs of both sexes, approximately 3 months of age, have shown that the organ contains at least two types of non-lymphoid cells: epithelial reticulum cells and so-called interdigitating cells. The latter have been observed in the inner part of the cortex and are morphologically characterized by an irregularly shaped or kidney-shaped nucleus, many tubulovesicular cytoplasmic structures accumulated mostly within the cytocentre as well as by finger-like protrusions of the cytoplasm. These interdigitating cells are in close contant with neighbouring lymphocytes with partly destroyed pycnotic nucleus.     

Osmium-zinc iodide reacts with interdigitating cells in the mouse lymph nodes and spleen.

It is known that epidermal Langerhans cells react with osmium-zinc iodide (ZIO) mixtures; therefore they can be visualized by this histochemical method. In the last few years it has been shown that Langerhans cells are closely related to the class of interdigitating cells (IDC) which are antigen presenting cells located in the T-dependent areas of lymph nodes and spleen. In this study the reactivity of murine IDC to ZIO has been assessed. Results demonstrate that ZIO procedure yields to a brilliant and selective staining of IDC. The reactivity pattern is quite similar to that previously observed in epidermal Langerhans cells. This finding gives further support to the concept that Langerhans cells and IDC are closely interrelated cell types.     

Surface ultrastructure and cytochemistry of isolated nucleoli from Novikoff hepatoma ascites cells

Surface ultrastructure and cytochemistry of isolated Novikoff hepatoma cell nucleoli were examined using scanning electron microscopy (SEM). Nuclear preparations were examined at 15 sec intervals during the sonication procedure for isolation of nucleoli. In the initial stages of nuclear disruption the nucleoli were attached to large chromatin masses. A compact nucleoprotein nucleolar stalk relatively resistant to shear was observed in association with many nucleoli. Further sonication disrupted these structures and left tightly coiled, helical filaments still attached to the purified nucleoli. These filaments were removed by DNase digestion but were resistant to RNase digestion. The present study provides a new perspective of nucleolar ultrastructure, its surface organization, and its relationships to other nuclear components.     

Ultrastructural differences of interdigitating cells in human lymph nodes

Eleven axillary lymph nodes from patients with different cutaneous disorders (systemic scleroderma, atopic eczema, psoriasis, hairy cell erythroderma, dermatopathic lymphadenitis) were examined by electron microscopy. In systemic scleroderma interdigitating cells (IDC's) showed typical ultrastructural features as well as intimate contacts with neighboring lymphocytes. In atopic eczema IDC's were characterized by widespread invaginations of the cell membrane, and an increase in tubulo-vesicular structures and microfilaments. Similar observations have been made in dermatopathic lymphadenitis. In psoriasis and hairy cell erythroderma. IDC's showed only a few interdigitations and invaginations of the cell surface. It is supposed that these structural changes in IDC's reflect the different immunological conditions of the diverse cutaneous disorders.     

Thymus of Rana perezi: presence of interdigitating cells

In the thymus of Rana perezi, as in other anuran amphibians, there exist two different portions, cortex and medulla. In both sections epithelio-reticular cells are observed as are lymphocytes, macrophages, and granulocytes. In addition, the medulla shows cysts and secretory, myoid, and hypertrophied epithelio-reticular cells. In the cortex, plasma cells and interdigitating cells were also observed. Interdigitating cells make contact with lymphocytes. This finding provides morphological support for the hypothesized role of interdigitating cells in antigen presentation.     

Ultrastructure of tumors arising from Schwann cells]

Ultrastructural changes have been studied using 67 tumors originated from the Schwann cells. Tumors were induced by means of methylnitrosourea injection with a week intervals. Both benign (fascicular and reticular) and malignant neurinomes were obtained. Main morphological changes were found in the Schwann cells. The tumor cell ultrastructure appeared to be definetely related to the degree of the tumor maturity. The results obtained may suggest that the fine structure of neurogenic tumors is also characteristic of their normal prototype--the Schwann cells.