The G0 ⇆ G1 transitions of human lymphocytes as monitored by quantitative14C-uridine autoradiography and high-resolution image analysis

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Abstract
Human lymphocytes, transferred in culture into medium conditioned with phytohemaglutinin, were studied with the combined use of quantitative 14C‐uridine autoradiography and high‐resolution image analysis. During the first 24 h before the onset of DNA synthesis it was possible to study pure G0 and G1 populations. The return of the proliferating cells into the G0 state was clearly monitored in an RNA synthesis rate/DNA content plot during 1‐week growth. On days 3–6, the proliferation decreased progressively, and more cells accumulated in the quiescent G0 state. Geometric, densitometric, and textural parameters evaluated from the Feulgenstained nuclei of the same cells indicated that the decondensation/condensation processes of the nuclear chromatin during the G0 °CG1 transitions paralleled the RNA synthesis activity. The results help to associate descriptors of nuclear morphology, as derived from image analysis, with functional parameters during activation and return to quiescence of human lymphocytes.