The propagation of a murine leukemia virus (Rauscher) in a kidney cell line, derived from a rat with lymphoid leukemia, was studied. A complement-fixing (CF) antigen reacting with Rauscher immune sera was detected at various passage levels, which correlated with the visualization by use of electron microscopy of viral buds and viral particles in different stages of maturation in all passages. Five-month-old monolayers continued to shed virus and to yield high CF antigen titers. The cell-free supernatant fluid from cultures of the 14th passage was shown to be infectious for a normal rat kidney cell line, as evidenced by the appearance of the CF antigen in this line. Interferon production was not demonstrated in infected cultures. The overall data indicated that rat kidney cells could be used to propagate Rauscher virus in a carrier state. The long-term propagation of Rauscher murine
A method of staining thin sections with lead hydroxide which enhances both resolution and contrast was described by M. L. Watson (1958) and is now undoubtedly in routine use in many laboratories.It is the purpose of this report to present a simplification of this method which eliminates the lengthy procedure of preparing the lead hydroxide reagent and the necessity of maintaining a COrfree atmosphere during the staining interval. On exposure to air, lead hydroxide forms lead carbonate, which may contaminate the specimen grid. In the procedure presented here it is believed that the reaction leading from lead acetate to lead hydroxide occurs in the specimen section. In any case it was only on rare occasions that a minimal amount of fine precipitate, presumably of lead carbonate, could be observed in the tissue.The tissue represented in the accompanying plates was prepared in the following manner. The pancreas of an 8 day old posthatched chick was diced and fixed for 1 hour in chrom-osmium solution (Dalton, 1955; Zeigel, in press). The small blocks of tissue were then immersed in 10 per cent formalin for 1 hour and dehydrated in a graded series of ethanols. They were infiltrated with, and embedded in, a 3:1 mixture of n-butyl to ethyl methacrylate which was catalyzed by 0.25 per cent benzoyl peroxide at 80°C. Sections were cut with a Porter-Blum microtome using a diamond knife and picked up from a 30 per cent acetone-in-water solution on formvar-coated Athene type grids.The sections are stained in the following manner. A saturated solution of lead acetate in boiled distilled water is maintained in a glass stoppered bottle so that a visible number of undissolved crystals remain at the bottom of the bottle. After several drops of the solution have been removed, the reagent bottle should be refilled to the top with boiled distilled water, thus eliminating any air pocket at the top of the bottle. It is thought that this prevents crystals of lead carbonate from forming on the surface of the reagent and thus decreases the possibility of contaminating the grids. With a
Electron microscopical observations on the relationship of the Golgi region to other intracellular organelles in certain protein-secreting cells have substantiated and extended existing hypotheses. In micrographs of several cell types, the juxtanuclear Golgi regions were observed to be closely associated with nuclear "pores." The "transition elements" of the ergastoplasmic membranes possess "blebs" which may represent a transport process facilitating the movement of intracisternal contents into the Golgi zone. A "blebbing" process of this nature may be one source of the small variety of Golgi vesicles. Zymogen granules of different densities were observed and their significance was postulated. Light Golgi vacuoles were observed. It is suggested that these vacuoles represent accumulations of relatively fluid material segregated from the secretory product in these cell types. These hypotheses from inferential evidence are discussed and extended.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.