Reliability and significance of DNA measurements in interphase nuclei and division figures in histological sections.

ABSTRACT

DNA contents from single cells at interphase and division were analysed in histological sections and in imprints from 73 breast cancer specimens. Fetal livers from 18 terminations of normal pregnancies provided the standard for truly mitotic prophases, metaphases and telophases. The reliability of DNA quantities from image microphotometry was improved using paraffin-embedded tissue samples from which 4, 8 and 15 microns slices were Feulgen stained. Imprinted replicas from the mirror surface of each freshly cut specimen provided matching domains and represent the crucial approach in this project. A close positive relationship was observed between interphase nuclei in 8 microns sections and their imprinted counterparts (r = 0.992; n = 73). Interphase nuclei in 4 microns sections yielded insufficient DNA contents when compared with the imprints (r = 0.815; n = 21) and with endogenous lymphocyte nuclei. This 2 cDNA standard also calibrated 232 mitotic figures to 3.91 +/- 0.01 c in 15 microns sections from fetal liver. Prophases, metaphases and telophases were slightly scattered (coefficient of variation = 0.04 each). The 0.09 c deficiency to plain 4.0 c was read as an artifact from sectioning. However, the methodical bias did not challenge the most irregular DNA distribution profiles recorded from chromosome division figures (CDFs) in 15 microns sections of breast cancers. Poorly differentiated and aggressive breast cancer (Auer type IV, Zetterberg type A) exhibited a 4.5 c exceeding rate of 82.24% from a total of 752 CDFs in 10 randomly selected cases. Well differentiated, slowly growing cancer with diploid interphase nuclei (Auer I, Zetterberg D) surprisingly showed a 4.5 c exceeding rate of 29.26% from a total of 173 mitoses and CDFs in 10 randomly selected cases. The bulk of data beyond the mitotic 4.0 c level discriminates biological bias from methodical impairment. We concluded that 8 microns sections are sufficient for human interphase nuclei, whereas a depth of 15 microns preserves intact mitoses and CDFs.