OBSERVATIONS ON ORAL TUMORS IN VITRO. 2. KARYOBIOSIS IN STRAIN KB CELLS

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.

Electron microscopy of oral cells in vitro. II. Subsurface and intracytoplasmic confronting cisternae in strain KB cells

Two special areas involving membranous components in strain KB cells were studied by electron microscopy. The first area described is that of the subsurface regions of two apposing cells in which flattened cisternae (one cisternae in each subsurface region) with membranes spaced 110-230 A apart were found in a confrontation alignment. The long dimension of the profiles of these cisternae ranges from 0.5 to 2 micro. At these intercellular contact areas, each cisterna is closely applied to the adjacent plasma membrane; the intervening space is 60-100 A. We have named the cisternae in these roughly symmetrical areas of cell contact the subsurface confronting cisternae. Communications between these cisternae and those of the rough-surfaced endoplasmic reticulum also were observed. The second area described is that of the intracytoplasmic confronting cisternae. These cisternae were observed as oval or round images about 0.3-1.4 micro in diameter, each image being composed of a pair of concentrically arranged confronting cisternae with membranes spaced 200-400 A apart. The apposing membranes of the two confronting cisternae are electron opaque, smooth, and free of ribosomes, whereas the unapposed membranes are less dense, scalloped, and associated with ribosomes. The spacing between the two intracytoplasmic confronting cisternae is 70-110 A.

The circumfusion system for multipurpose culture chambers. I. Introduction to the mechanics, techniques, and basic results of a 12-chamber (in vitro) closed circulatory system

A self-contained mechanical system for circulating nutrient fluid through 12 tissue culture chambers is described in detail. This system utilizes nonperforated cellophane membranes in the chambers which separate the circulating nutrient from the tissue culture environments. The nutrient, therefore, is dialyzed through the cellophane of each chamber; some cell products are retained in the microenvironment between the closely apposed cellophane and cover slip, whereas the other cell products move from chamber to chamber in the circulating nutrient. The resultant environmental conditions directed by the circumfusion systems are highly favorable for maintaining the differentiation of chick embryo tissues over protracted periods; a number of micrographs are shown.