the effect of dietary sucrose on dna formation in rat liver and kidney compared with that of starch was studied. male, weanling rats were fed for 6 and 14 days on diets containing 68% 'sucrose or 68% starch, and liver and kidneys were examined for 1ilie amount and rate of formation of dna; and also for content of fat, protein, and moisture. food intake and weight gain were estimated. sucrose fe...

Differentiation of nerve cells and other elements in the developing central nervous system has been studied histologically in materials stained by various techniques especially by silver impregnation. The time sequence of cellular transformation or cytodifferentiation have been deduced from the presence of transitional forms. However, the interpretation of the transitions in structure have alwa...

Reichard and E&born (1) demonstrated that rats selectively incorporated thymidine-N16 as deoxyribonucleic acid thymidine, and their observation has been extended by numerous investigators to include many organisms and several isotopic labels. Tritiated thymidine has been particularly useful as a means of marking DNA for study by high-resolution radioautography (Z), and the histological distribu...

HE use of tritiated thymidine (H3T) has, in recent years, become quite widespread in many types of biological research. Because thymidine is a specific precursor of DNA, its direct and exclusive incorporation into chromosomes permits analysis of their behavior and metabolism during the mitotic cycle. Its incorporation is revealed through the use of radioautography, for which purpose tritiated t...

IN RECENT YEARS many papers dealing with DNA synthesis in short-term cultures of human peripheral blood”6 have appeared. There has been increasing evidence that the small lymphocytes under stimulation of phytohemaglutinin1’ 9 and other substances10’2 are able to proliferate and produce mito515, but very few researchers have tried to investigate the time sequence of the DNA synthesis in the inte...

Cytoplasmic D N A is known in a number of cell types. Hoff-JCrgenson and Zeuthen (7), using a microbial bioassay method, reported the presence of cytoplasmic D N A in frog eggs. Later, Hoff-J~6rgenson (8) and Elson et al. (4) indicated that sea urchin eggs contained a D N A reserve in the cytoplasm. Using autoradiographs of whole cells, Scherbaum (21) described cytoplasmic labeling in Ha-thymid...