Nucleolar organizer regions in seminoma and intratubular malignant germ cells

Nucleolar organizer regions (NORs), as demonstrated by a silver-colloid staining technique, have been counted in 71 primary testicular seminomas (typical seminoma (TS) 31, high mitotic index seminoma (HMIS) 24, and spermatocytic seminoma (SS) 16) and ten seminomas metastatic to retroperitoneal lymph nodes. Mean NOR counts were 14.36 for TS; 17.66 for HMIS; 10.89 for SS; and 17.70 for metastatic seminoma. Analysis of data using Student's unpaired t-test showed a significant difference between the NOR counts obtained from TS, HMIS, and SS. Furthermore, there was a statistically significant difference between NOR counts in metastatic seminoma when compared with TS and SS but not HMIS. The association between tumor proliferation rates and intranuclear NOR numbers is discussed. In addition to a numerical variation, the NOR distribution throughout the nucleus was noted to be different in SS when compared with the other varieties of seminoma studied. The pattern observed had some features similar to those seen in cells of the spermatogenic series. The NOR technique was also applied to 19 cases of intratubular malignant germ cells (ITMGC). It was shown that these malignant cells were easily identified using this staining method and that the NOR distribution was similar to that seen in TS and HMIS. The mean NOR count in ITMGC was 16.41. This was significantly different from that of TS but not HMIS.