Abstract
Peripheral blood of rabbit was subjected to the following hypotonic treatments in addition to controls: (1) 3:2 blood or plasma-distilled water; (2) 0.2 M sucrose; (3) 0.95% sodium citrate; (4) Ohnuki's medium (Nature (London) 208: 916. 1965). The cells were smeared, fixed in methanol-acetic-formalin and stained by means of the Feulgen reaction. Cytophotometry was carried out in the Barr and Stroud integrating microdensitometer. The results show that the cells subjected to hypotonic media increase their chromatic load, the mean values being 7-12% higher than the controls. These results reinforce previous suggestions that any change in the physical state of deoxyribonucleoprotein molecules brings concomitant changes in the reactivity of their dye-binding sites and, moreover, that this increase is correlated with (1) diffusion of the deoxyribonucleoprotein complex and (2) increase of the mean nuclear size. Therefore, under the conditions used, the more diffuse the nuclear content, the higher the apparent deoxyribonucleoprotein value.