Uterus and endometrium: Flow cytometric DNA analysis in endometriotic tissue compared to normal uterine endometrium

Endometriotic tissue sometimes shows an invasive pattern. but the growth regulation of the tissue is insufficiently characterized. In a research programme on factors regulating endometriotic growth, the DNA ploidy status and S-phase fraction (SPF) were studied. Fresh-frozen endometriotic tissue from 14 women and endometrium from 11 of them were studied using flow cytometry. A clear diploid pattern was seen in most cases of endometriotic (8/14) and endometrial (8/11) samples. In the remaining cases the G0/G1 peak was broad and skewed, which might indicate a near-diploid cell population. To clarify this, a second group was studied, consisting of 29 formalin-fixed endometriotic samples from 22 women and endometrium from five of them. All these samples were diploid, with one having a broad G0/G1 peak. No convincing difference in SPF between endometrium and endometriotic tissue was found, as the calculations had to be handled with caution because of debris in many samples. Although the study of fresh-frozen samples gave some indications of differences in DNA ploidy status, flow of cytometric DNA analysis of formalin fixed samples of endometriosis showed a diploid DNA pattern in all samples. In conclusion, DNA flow cytometry did not show a convincing aneuploid DNA pattern in endometriotic tissue.