George G. Rose

Merkel cell in human and rat gingiva.

Abstract In the basal and/or suprabasal cell layers of human and rat gingiva, specialized epithelial cells (Merkel cells) were rarely observed with the electron microscope. They were less electron-opaque than keratinocytes and had a decreased number of desmosomes and tonofilaments. Small osmiophilic secretory-like granules were eccentrically located in the cytoplasm of the Merkel cells on the side apposing intraepithelial neurites. However, the specialization of gingival Merkel cells as receptors did not appear to be as high as the epidermal Merkel cells.

Electron Microscopy of Solitary Cilia in Human Gingiva and Rat Oral Mucosa

An electron microscopic investigation of human gingiva and rat oral mucosa revealed the presence of solitary cilia primarily in the germinative layer of the epithelium. The cilia were infrequently found in the stromal cells of the lamina propria. These cilia were associated with the diplosome but lacked the central fibrils normally found in motile cilia.

Fetal mouse lung in circumfusion system cultures.

SummaryFetal mouse lungs were cultivated, using the dual-rotary circumfusion system for tissue culture, and their histotypic development was surveyed for 75 days by phase-contrast and electron microscopy. Alveoli, terminal bronchioles and alveolar macrophages were photographed periodically with still and time-lapse phase-contrast microscopy. Their histotypic appearance was confirmed by electron micrographs of the 1- and 2 1/2-month-old specimens. These revealed typical alveoli surrounded by a basal lamina and composed of types I and II pneumocytes containing various lamellar-body forms within the type II cells, the alveolar lumen, and the alveolar macrophages. There was a shift from almost all type II cells in the 1-month-old alveoli to the presence of frequent type I cells as constituents of the alveoli in the 2 1/2-month-old cultures. The terminal bronchioles were tubules consisting of ciliated cells with Clara cells interspersed between them. The ciliated cells contained as many as 30 cilia or basal bodies per section and numerous microvilli. They were attached to each other and to the Clara cells by junctional complexes and accessory desmosomes which were generally in the apical ends of the cells. The Clara cells typically had glycogen granules interspersed between lamellae of the endoplasmic reticulum, contained numerous well dispersed mitochondria, occasional lysosome-like granules and crystalloid bodies which appeared to be tubular. Some Clara cells presented a moderately dense secretory granule in the center of the whorl of the endoplasmic reticulum.

Terminal bronchiolar-alveolar (TB-A) units in circumfusion system cultures

SummaryLong-term (more than 75 days) recirculating circumfusion system cultures of 15-day fetal mouse lungs gave rise to terminal bronchiolar-alveolar (TB-A) units detached from the respiratory tree. TB-A units established in serum-free microenvironments under reconstructed cellophane membranes became especially flat and optically accessible in fast-flowing 6-chamber systems devoid of a pulse pressure. Time-lapse cinephase movies showed that the alveoli were maintained debris-free by the phagocytosis of alveolar macrophages which entered the alveoli by penetrating the pneumocytic walls. The terminal bronchioles with active ciliary cells communicated with the alveoli and together they formed a flat fluid-filled tubule-like closed system composed of ultrastructurally typical differentiated cellular constituents, viz. types I and II pneumocytes, endocrine-like cells, ciliary cells, Clara cells, and septal cells. TB-A units were observed throughout 150 days of cultivation at which time their phase morphological differentiation remained stable and their functional activity observable as smooth-muscle contractions, ciliation, and alveolar macrophage phagocytosis. A 1000-foot motion-picture film complementing the descriptions of the TB-A units and the alveolar macrophages in the text is deposited with the Motion Picture Film Rental Collection of the Tissue Culture Association, Inc., at the W. Alton Jones Cell Science Center, Lake Placid, New Hork.

Human Gingival Fibroblast Production of Interferon

Three human gingival fibroblast cell lines were used to determine whether they could be induced by a synthetic RNA and super-induced by metabolic inhibitors to produce interferon (IFN-β). When established procedures were followed for human fetal or newborn skin fibroblast cell lines, the adult gingival fibroblasts produced comparable amounts of IFN-β. It was shown that the superinducers alone would not cause an IFN-β production response, and that the absence of serum in the production medium also inhibited the production of IFN-β. The effect of IFN-β on cell growth was carried out in T-flasks seeded with 105 HEp-2 cells. After one and two wk, the cells of triplicate control flasks and triplicate flasks containing various dilutions of the production media were enumerated to determine a cell multiplication inhibition (CMI) value. A correlation between the IFN-β content and the CMI effect, however, was not obtained, and it was concluded that other CMI agents, possibly more potent than the IFN-β, were being produced by the stimulated human gingival fibroblasts. Cell protein assays which gave a high ng/ cell protein content correlated with TEM micrographs which showed clusters of complex lysosomes, primarily in cells cultured in the IFN-β-containing nutrient. However, since commercial IFN-β initiated no such lysosomal response, it was further concluded that the complex lysosomes were due to CMI agent(s) other than IFN-β.

The subcellular organization of human gingival epithelium cultivated in circumfusion systems

Abstract The submicroscopic organization of the emigrating epithelium from two specimens of adult gingiva cultivated in dual-rotary circumfusion systems was investigated. After 21 days, the cultures were fixed and the epithelial outgrowths were embedded and sectioned in planes both vertical and horizontal to the surface of the cover slips for observation by phase-contrast and electron microscopy. Three types of cells were identified: (1) basal-like, (2) prickle-like, and (3) desquamative cells. The basal-like cells were comparatively smaller than the prickle-like cells and were characterized by prominent Golgi complexes, centrioles and scant tonofilaments and desmosomes. The basal-like cells overlaid basal lamina-like structures applied to the surface of the mica cover slips and contained hemidesmosomes. The broad prickle-like cells were characterized by their dense arrays of tonofibrils, increased numbers of desmosomes and microvilli between wide intercellular spaces, several kinds of lysosome-like bodies, and large accumulations of microgranules. Mitochondria with myelin-like figures were frequently encountered in both upper and lower epithelial cells. However, keratohyalin granules were not observed in this study. Desquamative cells had characteristic cytoplasmic condensations on the inner leaflet and contained vesicles of various sizes and shapes. These observations demonstrated that the retention of histiotypic patterns observed in living cells by phase-contrast microscopy was similarly maintained at the ultrastructural level.

A current interpretation of the anatomy of the mammalian cell

Publisher Summary This chapter provides an overview on the current interpretation of the anatomy of the mammalian cell. It discusses various membranous components. The plasmalemma of a living cell cannot be the complete barrier that superficially it appears to be. With the electron microscope, these surface cell membranes are viewed in cross section as trilaminar structures of relatively uniform width. Mitochondria is divided into two compartments: (1) the lesser compartment, which lies between the two parts of the double membrane and includes the area between the two leaves of the cristae projecting into the mitochondrion, and (2) the greater compartment, which is the area internal to both double membranes and between the cristae. The endoplasmic reticulum is a cytoplasmic system of closed unit membranes surrounding flattened or dilated cisternae. Similar to the endoplasmic reticulum, the Golgi complex is part of the cytoplasmic vacuolar system. Lysosomes are round or oval small bodies that are enclosed by a single unit membrane. Annulate lamellae are the stacks of membrane. Filaments, microtubules, centrioles, ribosomes, lipids, glycogen, and chromatin are general non-membranous components, whereas, keratohyalin granule is a special non-membranous components.

Effect of X Radiation on Rat Fetal Oral Mucosa in Tissue Culture

Cultures of oral mucosa from 15- to 17-day-old rat fetuses were placed under cellophane membranes on cover glasses of Rose chambers to determine the action of low doses of X radiation on the oral epithelial cells, exclusive of mitotic phenomena. The principal characteristic of the emigrating cells in control cultures was established. The most important changes in surviving cells of the irradiated cultures were the formation of multinucleated giant cells, cellular vacuolization, and movements of the cell membranes (zeiosis and pericyclosis). Even with the low doses, there was a decided inhibition of growth.