Re-evaluation of the Quantity of DNA in Cell Nucleus of Two Animal Species by Microspectrophotometry and Autoradiography

Abstract

Microspectrophotometric evaluation of the DNA content of cell nuclei and ³H-thymidine autoradiography were carried out on the cells from cerebellums, thymus, glandular stomach, liver, and kidney of embryonic, suckling, and adult Syrian hamsters and Buffalo rats. The results obtained from this study were as follows: 1) In both hamsters and rats, the cells with diploidDNA (2C) showed the main modal peak in various organs examined of embryonic to 6-month-old animals. 2) In liver tissues, tetraploid cells (4C) began to appear in the 3-day-old animals and increased gradually in number until 6 months old, 40% or more of the cells showing tetraploid value of DNA. 3) No cells with intermediate or extra DNA were found in tissues examined during the growth period of animals, and neither octaploid nor higher nuclei appeared even in liver tissues of the adults. 4) ³H-thymidine labeling index showed high percentages in organs of embryo to 1 day after birth. 5) ³H-thymidine labeling index rapidly declined 1 week after birth in all the organs except in the cells of glandular stomach. 6) There is a close correlation between labeling and mitotic indices and the distribution pattern of DNA value. From these data it would be supposed that the appearance of the cells with extra or intermediate DNA value is due to the existence of the cell in S-phase.