Microcinematographic and Autoradiographic Study on the Pattern of 3H-Thymidine Uptake in the Life Cycle of the Individual Cell of the HeLa Strain In Vitro23

Abstract

Cinematographic and autoradiographic studies of individual cells of the HeLa strain in culture were made during periods of about 67 hours. Each portion of the cell life cycle showed some variation from one cell to another. Two stages of the rate of ³H-thymidine uptake were observed. One was characterized by low rate (S₁), and the other by high rate(S₂). The duration of the S₁ stage was longer than that of the S₂. The rate of ³H-thymidine uptake in the S₁ stage underwent a logarithmic increase. The nature of the low rate of ³H-thymidine is discussed.