Cells in tissue cultures usually leave from the mass of tissue and migrate to the periphery of the medium where they may extend and flatten considerably. Under these conditions they have been widely used for the study of their inner structure under the light microscope, in vivo as well as in fixed and stained preparations. In the present paper some results will be given of an electron microscop...

It is well known that the embryonic cells dissociated with the treatment of trypsin , when cultured on a gyratory shaker, tend to form a definite histoformative structure (Moscona 1961). The aggregation patterns, or the size, number, and shape of these cell aggregates, are characterized by the types and origins of the cells . These aggregates are formed through the cell-to-cell contacts which m...

The antibiotic vancomycin was effective in preventing bacterial contamination during studies with psittacosis and trachoma (PT) agents. This antibiotic was not toxic to chick embryos at 80 mg per egg, or to HeLa 229 cells cultivated in a medium containing 3,200 mug/ml of vancomycin; however, it was toxic to LLC-MK2 cells at a concentration of 1,600 mug/ml. Vancomycin did not affect the growth o...

Single-channel K+ currents were studied in the myotubes from the chick embryo grown in tissue culture for 4--9 days by employing the patch clamp technique. The "cell attached" configuration was used and the pipette was filled with a solution containing 3 mmol.l-1 K+. The channels exhibited a high conductance of approximately 90 pS and the probability of finding them open increased by an e-fold ...

Dedifferentiated chick embryo chondrocytes (Castagnola, P., G. Moro, F. Descalzi-Cancedda, and R. Cancedda, 1986, J. Cell Biol., 102:2310-2317), when transferred to suspension culture on agarose-coated dishes in the presence of ascorbic acid, aggregate and remain clustered. With time in culture, clusters grow in size and adhere to each other, forming structures that may be several millimeters i...

Infection of chick embryos wih either Newcastle disease virus or mumps virus and infection of BGM cell cultures with mumps virus result in the elaboration of chemotactic activity for neutrophils and macrophages. These factors cannot be found in lysates of uninfected cells. They do not appear to be associated with the viral particles per se, but rather are present in virus-free supernates from i...

In a previous communication (2) a description of an acid-fast organism isolated from human and rat leprous lesions was reported! Embryonic chick tissue-cultures were used as the isolation medium. Later reports (3,4,5) have dealt with the influence of various environmental factors on the tinctorial characteristics of the organisms that were isolated. The present communication deals with results ...

Cells were isolated from the somite mesoderm and from the unsegmented (presomite) mesoderm of early chick embryos and exposed to actinomycin D in single cell culture. Actinomycin D inhibited proliferation in cell cultures derived from the unsegmented mesoderm, although the same concentrations of this antibiotic did not inhibit cultures derived from the somite mesoderm. This differential sensiti...

During studies on the fate of leprosy bacilli in the fibroblasts of lepromatous lesions (1), occasion was taken to utilize the bacilli from any extra portions of the nodules in trying to establish experimental infections in chick embryos and chick tissue cultures. Due to the two different types of experimental material, the literature, methods, and results pertaining to each will be summarized ...

1. The plasma of guinea pigs treated by injections of rat sarcoma exhibits a toxic action in tissue culture preparations on the cells of both rat sarcoma and rat embryo skin. Similarly, the plasma of guinea pigs immunized by injections of rat embryo skin is toxic for cells of both types. 2. Injection of rat blood immunizes against both sarcoma and embryo skin, although not so strongly as inject...