Search PubMed⌕ Search

Biomedical subjects

F R Denys

Publications and source records attributed to F R Denys.

62 records · Page 4Linked to original sources
PubMed1976

Ultrastructural features of the verruciform xanthoma.

The verruciform xanthoma, a rare lesion of the oral cavity, was studied by light and electron microscopy. The major cell type associated with the lesion was shown to contain appreciable amounts of lipid and was characterized as a macrophage. It was characteristic of the endothelial cells associated with subepithelial capillaries to exhibit multiple basal laminae. A rather unusual observation was the migration of lipid-filled cells into the stratum germinativum of the overlying epithelium.

Adult↗
PubMed1976

Electron microscopic observations of "keratin pools" in chronic hyperplastic oral mucosa.

"Keratin pools," previously characterized clinically and histochemically in the superficial epithelium of chronic hyperplastic oral mucosa, were studied by light and electron microscopy. These occured as small beaded and larger coalescent masses which varied in metachromasia. Ultrastructurally, the "keratin pools" consisted of electron-dense, amorphous or finely-granular material developing and coalescing, chiefly as extracellular deposits. The "pools" frequently possessed a layered arrangement alternating with cells having distinct tonofilaments, desmosomes, and definite cell membranes. Occasional bands of filamentous-like material, possibly representing tonofilament bundles, were observed in some "pools."

Aged↗
PubMed1975

Ultrastructural characteristics of mast cells from a canine mastocytoma maintained in vitro.

Mast cells obtained from a canine mastocytoma were maintained in cell culture for a period of 11 weeks. Samples of these cells were harvested for electron microscopic examination after 9 weeks in vitro. Although the overall morphologic appearance was sufficient to allow their identification as mast cells, the tumor cells differed in several respects from descriptions of normal tissue mast cells. In contrast to normal tissue mast cells, the tumor cells exhibited peripheral accumulations of microfilaments, randomly dispersed microtubules, and small clusters of smooth endoplasmic reticulum. The tumor mast cells also presented three different granule types: spherical granules with an amorphous and electron dense matrix; irregularly shaped granules possessing a limiting external membrane and an internal matrix containing laminated and/or coiled structures; and granules containing loosely coiled, unorganized membrane structures similar in appearance to myelin whorls. The canine mastocytoma is an excellent source of mast cells as they can be obtained in large numbers without contamination by extraneous cell types and the cells can be maintained in vitro for extended periods of time.

Animals↗
PubMedDate not supplied

Ultrastructural study of liposome uptake by M cells of rat Peyer's patch: an oral vaccine system for delivery of purified antigen.

Liposomes (phospholipid artificial membrane vesicles) have been used in targeted drug delivery and recently in the development of oral vaccines using purified soluble antigens for the induction of mucosal immune responses. Although the mechanisms by which liposomes promote the induction of responses to soluble antigens have not been clearly shown, it has been suggested that these vesicles, when given orally, are taken up by M cells for delivery of antigen to underlying lymphoid cells of the Peyer's patch. This study investigated in vivo the uptake of liposomes by cells of Peyer's patch. Following exposure of surgically constricted segments of rat small intestine to small unilamellar liposomes or gold-labelled solid core liposomes, Peyer's patches were removed, fixed, and processed for examination by transmission electron microscopy. Sections of Peyer's patch from experimental animals showed M cells with endocytic vesicles containing liposomes. Vesicles containing liposomes were also observed between M cells and lymphoid cells. These results indicate that intact liposomes are endocytosed by M cells and provide evidence for a possible mechanism by which M cells deliver antigen to lymphoid cells in the Peyer's patch. These findings support the potential usefulness of liposomes in oral vaccine development.

Administration, Oral↗